Captain America: The First Avenger/WMG

Howard Stark accidentally caused the "Mutant Problem"
If we assume that the x-men movies and the Avenger movies take place in the same universe than it is possible that the cosmic cube caused the surge in mutations seen between X-men: First Class and the other movies. In First Class, Shaw claimed that mutants were the children of the atomic bomb. Now, of course there were mutants before that but most likely not as many (if there were, than the government would have known about them before Charles revealed himself). In Iron Man it is mentioned several times that Howard Stark worked on the atomic bomb. At the end of Captain America, Howard recovers the cube from under the sea. Red Skull thought the power of the cosmic cube was meant to be seized by superior men. Put it together and what do you get? Howard Stark used Cosmic Cube technology to create the atom bomb and the atom bomb acted as a sort of catalyst to bring out the powers of the ‘superior men.’ And in the X-men universe what is the scientific name for mutants? Homo Superior.

Gabriel Jones of the Howling Commandos is a young Nick Fury
He's smart, skilled, and one of the most badass of the Howling Commandos. Its clearly implied that the SSR would later form the basis for the organization SHIELD. And, they have access to blood samples from Steve Rogers with which to attempt to recreate the super soldier serum. So, my theory: like the rest of the Commandos, Gabe goes off with the 107th and the SSR to form SHIELD. He becomes one of the best of their operatives, if not the best. Good enough for two things. One, he's chosen as the recipient of one of the attempts to recreate the SSS, that doesn't work particularly well (aside from retarding aging, probably only discovered later). And two, when Gen. Chester Phillips dies or retires, he becomes his successor as Director of SHIELD, taking on the alias used by the director, "Nicholas Fury." (Try envisioning Tommy Lee Jones with an eyepatch if it helps.)
 * Alternatively, Gabe is Nick's father or grandfather and passed on a weakened version of the serum to his descendants.
 * It doesn't even have to be that complicated. In the comic Nick Fury was the leader of the Howling Commandos and his life is unnaturally extended by some kind of serum (whose name eludes me at the moment, could easily be folded into a diluted version of the SSS for the films, and I think it actually is in Ultimate Marvel). It's possible, even likely that when Gabe Jones is taken in for covert work, he's given a codename and he pick Nick Fury cause it sounds badass.


 * Or it is Nick Fury (as leader of the HC ) and not gabe Jones (or did they use his name in the film?

The ARC Reactor Howard Stark builds in the 60s is the result of studying the Cosmic Cube
Perhaps the Cube is a perfected Vibranium ARC Reactor. Tony's father spends 2-3 decades studying it before building the massive prototype.
 * I've been thinking about it, and this is what I've collected, the element Tony was trying to create in Iron Man 2 was probably more or less the same as the one in the cube. Think about it, his father studies the cube, makes the model and keeps it in a video for Tony to find. Howard could've done it himself, but as he said in the video, his time didn't have the technology for it yet.
 * The novelization makes the claim that the materiel is vibranium which doesn't fly too well with caps shield. Unless thats what it was before Tony hit it with his homemade particle accelerator (because Cern can suck it apparently) and Tony converted it into a cosmic cube, vibranium hybrid element.
 * According to the post-credits scene in Thor, SHIELD hasn't exactly figured out what does the Tesseract do even with Tony Stark's help, and is still looking out for ways to utilize it, unwittingly playing into the hands of Loki who likely knows the true purpose and capabilities of the device.
 * However, other aspects of HYDRA technology could've been developed further. HYDRA Elite Mooks seem to use powered exoskeletons. Iron Man establishes that a miniaturized portable power source is perhaps the most important component to a successful suit of Powered Armor, so Stark could've had a more direct inspiration from their designs once he invented the arc reactor. Building a suit in a cave, with a box of scraps, requires that he is at least partially familiar with previous attempts to implement the technology.

The woman that tried to fool Steve at the end was Sharon Carter.
The setup is just too elegant: the first person he sees when waking is his next Love Interest. Plus her actress, Amanda Righetti, seems a little too big of star for such a small role- and she's already listed as filming The Avengers, and listed as Sharon Carter. Admittedly, the IMDB can be edited by the public, but not quite as easily as a Wiki.
 * Not anymore she isn't.
 * Being on The Mentalist doesn't make her a star. Natalie Dormer was on The Tudors and still wound up playing a bit character.
 * This troper believes the same thing. She does resemble Peggy a lot. We'll probably find out in the Avengers movie.

Peggy Carter is Tony Stark's mother.
Perhaps after the war she and Howard did end up "fonduing". This would give Steve a reason to dislike Tony, as Tony has his daddy issues for not warming up to Steve right off the bat.
 * Uh, no. Tony's mom is Maria Stark.
 * But has that been confirmed for the movies? They've already played around with established canon, primarily through mixing classic and Ultimate storylines- as well as making Howard Stark himself something other than a complete bastard.
 * Uh, yeah? It was established in Iron Man 2 that Maria Stark is Tony's mommy. Howard calls to her to grab little Tony when he was trying to film for the Stark Expo.
 * Actually, the only thing that scene establishes is that Maria is either Tony's mother or stepmother.
 * Or' nanny.
 * Wasn't Maria mentioned as being Tony's mother in the clip show portion at the start of Iron Man 1?
 * It would be tricky to fit in the timeline, given Peggy and Tony's ages. Not impossible, but tricky.
 * Actually it would be pretty impossible. Peggy is hardly any younger than Howard Stark meaning she had Tony well into her fifties.
 * And how would that enhance the story, exactly?
 * Pshaw... You're talking like every WMG needs to make sense from every angle.
 * How about one angle, then? It doesn't makes sense age-wise, nor does it make sense as far as the characters go. Steve isn't a petty man that would be bitter about Peggy moving on and having a kid, and Tony isn't so immature as to dislike someone because they'd almost went on a date with his mother once. Their personalities are all the conflict fuel they need.
 * This troper wouldn't be surprised if Tony's mother is one of the dancing girls at Howard's presentation.

This movie, and all the other Marvel movies in this series, take place in the same universe as Indiana Jones
Because of all the shout outs to it. And they're both owned by Walt Disney now. And then we can make Crossover WMGs.
 * For example: Marion is related to Peggy.
 * Except Indiana Jones ISN'T owned by Disney, it's owned by Lucasfilm.
 * Well, the Skull does mention Hitler "digging in the desert for trinkets". Now, where do two of the three Indy movies take place?

The Red Skull cut off his own face in a fit of madness when he first injected himself
The side-effect of the early super-soldier serum wasn't physical deformity, but a temporary bout of agony, hallucinations and madness, similar to the DTs. Red Skull mutilated himself while he was undergoing a "bugs under the skin" sensation common to substance-abusers. Since the serum might have given him something like a healing factor, the redness was the result of him clawing the skin off repeatedly and it growing back as bright red scar-like tissue. Something like this happened to Ultimate Red Skull.

The Skull wasn't disintegrated, but rather transported to Asgard
Where he met up with a certain God of Trickery and gave him the genesis of a verrrry bad idea, which plays out in The Avengers.
 * Once he got to Asgard, he was put on ice and will be thawed, either as a prisoner or as a possibly useful pawn by Loki.
 * I posit one step further. All of the energy weapons used to disintegrate people were in fact transported to Asgard. All those soldiers and Hydra men were actually transported to Asgard thousands of years ago, and became the ancestors of the Norse gods. It would explain a lot about the similarities between Asgardians and humans, and why they have advanced technology (Hydra was the Nazi's science division).
 * Well, his "disintegration" does look a lot like the Bifrost being used. And he did refer to the Cube as "the jewel of Odin's throne room" -- given the interconnectivity of these movies, that's a very strong suggestion that the Cube is a piece of Asgard tech that was left behind after they were done fighting the Frost Giants all those centuries ago.
 * Possibly confirmed!
 * They might have to explain why he hasn't aged though. Transporting him to Jotunheim would make more sense to this troper and would also further the Red Skulls position as a dark mirror to Steve. (Frozen in ice after an accident then discovered and revived 70 years later.)

Cap is actualy the third to last Avenger
He is called the first beacuse he was born first but this makes him the oldest.
 * Wasn't Thor born centuries earlIer than Cap?
 * He was one of "Earth's Mightiest Heroes" before any other Avenger.

SHIELD was backronymed to honor Captain America
That's why they bend over backwards to come up with something decent for that acronym--they're paying homage to the weapon of the man who started it all.
 * Jossed by the first Iron Man movie which had the full name already exist while the acronym isn't thought up until the end of the movie.
 * No one can think of an acronym, its just right there! Coulson was likely using the long form because SHIELD likes to remain obscure.

Steve will yet have that last dance with Peggy.
Let's do the numbers. Suppose Peggy Carter was, say, 28 in 1943. That means she'd be 97 in 2012. Hence, not necessarily dead.
 * Please oh please let this happen.
 * Or she may have been killed during the war. There's no telling what might have happened.
 * I will be very disappointed if she does not turn out to be a founding member of SHIELD
 * To that effect, this troper would absolutely love to see an old photo hanging on the wall at SHIELD headquarters that features Peggy Carter, Howard Stark, General Chester Phillips, and Nick Fury sitting around a table together with a small gold plaque underneath naming them as the "Founding Members of SHIELD."
 * It seems more than likely that Peggy is deceased by the time Cap wakes up, given the rate at which WWII veterans (and people of that age) are dying; however, it might not be all bad. The first time Steve walks into those hallowed halls, a portrait of Miss Carter hangs in a place of honor... wearing a locket with a newspaper photo of Steve Rogers.
 * Or he has a dance with her niece Sharon Carter.
 * Better yet, Steve will get a chance to have a relationship with Sharon, but the sequel will end with Steve telling her that he has "one more thing left to do", as we then see her visiting an aged Peggy (preferably played by the same actress from The First Avenger, but using Benjamin Button-esque SFX to age her), and getting that last dance in.
 * One novelization of the The Avengers movie

The montage of hunting down HYDRA bases involved large amounts of fighting regular Nazis
Just for Rule of Cool and opportunity for exposition and characterization in later films and fanfiction.

Zola is still alive, and a cyborg.
Well in the comics he's a geneticist, and put his brain in a body with a camera for a head, and his face on a big screen on his chest. Sorta makes more sense if that body is the resualt of cybernetic modification. Zola would have been highly desirable by any number of nations for his research after the war, like many German scientists in real life.

HYDRA had/has Mind Control technology
Although it was limited. It involves big expensive machines where someone is strapped in and indoctrinated, and while they do render the poor saps involved into HYDRA fanatics, it generally compromises creativity to a severe degree. Said system is too expensive to use on Labourers and to destructive to use on agents or administrators (who are for the most part fanatically loyal) but is useful for producing soldiers.
 * Maybe that's what Dr. Zola was experimenting with when he had Bucky captive? Trying to use get him to become a Brainwashed and Crazy servant of HYDRA? In that case, it's fortunate that Steve found him before any further experimentation could happen.

HYDRA will be the/a villian in The Avengers
Not that bad, Loki needs Mooks, after all.

Cap was left in the ice for seventy years on purpose
If Skull returned from wherever the hell the Cube sent him anytime prior to the fall of the Berlin Wall, The Government wouldn't have given (insert offensive language here) over his war crimes - only his knowledge of HYDRA technology. He (like the other ratliners like von Braun and Strughold) would get a pardon and a new identity faster than you can say "Herr Doktor". And given that both "died" fighting each other, the government would probably decide it best to leave Cap where he is, having enough of Erskine's notes to realize that Cap would stay a Human Popsicle as long as necessary. Skull will pop up again in the second Avengers movie, running the American mutant death camps.
 * Epically unlikely, given the tone of every single MCU movie yet.
 * Then the MCU has some MAJOR differences from Real Life given what happened to brilliant Nazi scientists post-WWII. And you have to discount The Incredible Hulk, as the core of it is General Ripper wanting to create human WMDS with his "Bio-Force Experiments". The Hulk is almost the polar opposite of Cap - an indestructible monster as opposed to a paragon of humanity. Take That.
 * Missing the point and offensive. There is a *huge* leap from "one guy going to unethical extremes to make a superhuman weapon" and "deliberately leaving Captain America on ice, oh, and also, death camps."
 * There is also a distinction between "Real smart, but possibly complicit in violations of the Geneva Convention" and "Raving Megalomaniac who would happily Burn The World". Zola, I can see (and even then the Death Camp thing would never get off the ground). Schmidt? Not a chance.
 * Then what part will the mutants play in the MCU? They're basically the Civil Rights Movement's Fictional Counterpart. Cap would be on their side simply by nature of what he is - "Not a perfect soldier, but a good man", while Fury has compromised with monsters on numerous occasions simply because they have authority over him.
 * Firstly, assuming facts not in evidence; given the OOC licensing issues, there probably won't *be* any mutants or mutant issue in the MCU. Secondly, assuming facts not in evidence, as far as movie Fury making outright monstrous compromises. Put bluntly, until the movies actually put the slightest whiff of flagrant evil on that scale on the part of the US government, its laughable to just assume it exists. Again, "dubious experiments and hunting down one person who probably should be pursued anyway" *does not equal* "mutant death camps and intentionally leaving for dead a war hero."
 * Could you reference "the OOC licensing issues"? "The Mutant Problem" is a key component of the Marvel universe, and it's not going to be referenced in any way, shape or form for the MCU? Kinda odd. It'd be like having a DC universe without Superman.
 * The X-Men film rights are held by 20th Century Fox; the Captain America film rights (along with Iron Man and Thor) belong to Paramount. Maybe that's it? (Note that the Hulk rights, last I checked, belonged to Universal Pictures... but it seems like Ed Norton won't be playing the Hulk in Avengers anyway, so they'll probably reboot along with recast him.) Besides which, adding 'the mutant problem' to the series would be overburdening an 'arc' already dedicated to founding and following the Avengers, which is why the above movies are tied together; anything more than a passing reference would be saddling the Avengers films with something that should be (and is) already found in the X-movies. Also, Civil War sucked.
 * Marvel Studios specifically got back the rights to Hulk, and did before TIH even finished filming. Maybe before it started filming, reports have been conflicting. As for mutant rights being integral to the Marvel U, honestly, they are a giant Plot Tumor that has weighted down the setting for years. I am entirely glad to see the overly iron age cruft stripped away from the cinematic setting.
 * Fox(the firefly slayers - may they all die of gonorrhea and rot in hell) also owns the rights to Fantastic Four - and the movie they made of that was kinda lame. And Columbia owns Spider-Man. That eliminates the other three big Marvel titles - so what's left for the MCU after The Avengers?
 * More Avengers, obviously. Plus sequels and threequels to the current successful single-hero franchises: Iron Man, Thor, Captain America, maybe even rebooted Hulk. And of course the X-movies roll on, after First Class succeeded in regenerating interest in the mutants and such.
 * Also Luke Cage!

Bucky Barnes survives his fall off the train.
Firstly, they Never Found the Body. Secondly, when Cap rescues Bucky in the HYDRA base, he's strapped to an operating table, possibly having been experimented on with the imperfect Super Soldier Serum, enough to make him durable enough to survive the fall.
 * Though possibly not without losing an arm in the process ...
 * Actually mentioned on the commentary of the DVD....imperfect serum from Zola and all.
 * Yes we all know what is going to happen with Bucky. If you don't just search him on google and have the plot of a Captain America sequel spoiled.

The Cosmic Cube is an Asgard artifact
Not Asgardian, Asgard.

Jim Morita was a member of the 442nd Infantry Regiment before he was captured by Hydra.
Because it makes him a badass.
 * This seems likely, as at the time units were still segregated and there wouldn't have been a lot of options for a Japanese-American. The fact that he says he's from Fresno is sobering, since it's likely that he spent time in an internment camp prior to signing up (California being a big supporter of the 'exclusion zone' idea) and his family and friends may still be there.

The movie takes place in the Fallout universe.
Following the 'death' of the Red Skull, the 'defection' of Zola, and the acquisition of the HYDRA bases, the US military claims the technology developed during the war, particularly the laser-based weapons and body-armor. Reverse-engineering creates a more portable, more replicable, not quite as powerful power-source, allowing for mass production until the entire military is outfitted. In the face of an America with unprecedented military and technological might, the rest of the world stays silent when China begins its rise in hopes that the two countries will check each other; unfortunately the conflict turns hot, eventually plunging the globe into thermonuclear devastation. Remnants of HYDRA were assimilated into the US government for their expertise, but many retained their loyalty to their deceased leader and indoctrinated their descendents: The Third World War provided the pseudo-HYDRA agents with the opportunity to take control. They rename their new organization the Enclave, abandoning mysticism altogether in favor of extreme science (note all the 'subjects' in Raven Rock). More-or-less inspired by the fact that the suited-up HYDRA soldiers, with their glowing-blue weapons, reminded This Troper of the Enclave's laser/plasma weapons and sparking Tesla Armor... plus the Enclave evoking Nazis.

Red Skull isn't dead and will reappear as the villain...of Thor II, not Captain America II.
It's a no brainer Red Skull isn't dead and wasn't disintegrated by the Cosmic Cube. Rather, it seems that he was transported somewhere, to another world connected by Yggdrasil. This will be important in the second Thor film, where Red Skull will come out of whatever world he's been hiding on to make trouble for Asgard. This will also be the first time a villain from one movie has crossed over into another hero's movies. Given Red Skull's obsession with the powers of the gods, it'd make sense he'd try to get his hands on more Asgardian tech. By the end of the movie, however, Red Skull will be returned to modern-day earth (but it will free Cap up to have another of his villains take center stage for the second Cap film).
 * Or he'll return in the Avengers teaming up with Loki.
 * Except that Captain America has no villain more iconic than the Red Skull, or at least no-one that hasn't been compiled into other characters for The Movie. Look at this list and try to find a villain/villain group that's both unrelated to HYDRA and not too out-of-date or silly. Though  could be pretty cool...
 * Actually, there are several of Cap's villains that could work for the movies. Baron Zemo for one would be an excellent choice.
 * I assumed Zemo had been subsumed - essence-wise, if not directly - into the movie characters of Zola (Nazi's leading genius/supertech scientist) and movie-verse Red Skull (charisma, ability to lead massive organization of fanatics, Big Bad status, ect).
 * Heinrich Zemo has. Helmut Zemo hasn't.

Cap's shield only absorbs frontal attacks.
If the shield truly absorbed all energy, it would be useless as a weapon. Its impact against an enemy would be absorbed, so the enemy wouldn't be hurt and the shield wouldn't bounce back. Also, there's the question of what happens to the absorbed energy? It can't just keep absorbing energy forever, can it, until it has like fifty tonnes of TNT worth of energy sitting inside it, perfectly neutral? The answer: the shield is designed so that any blow from front-on gets absorbed, but any blow to the edge causes a certain amount of the absorbed energy to be released -- so that an enemy hit with the flying shield will actually be impacted with a great deal of kinetic energy, and the shield will (given the right trajectory) rebound all the way back to where it started.

Agents of the SSR founded SHIELD
IRL, the OSS was WWII-era spy organization that was decommissioned after the war, but several of its agent went on to found the CIA. Something similar happened in the MCU with the Strategic Scientific Reserve and SHIELD. Both have Strategic in their titles (as did the OSS) and have a spread-winged eagle against an oval as their logo, also like the OSS/CIA. Possible SHIELD founders are Dum-Dum Dugan, Gabriel Jones, Peggy Carter and Howard Stark.
 * And their first director is probably Chester Philips. I would be shocked if this doesn't turn out to be 100% canon
 * Howard Stark was already confirmed to be a founder in Iron Man 2, so this theory looks likely.

Steve wasn't the only Captain America
After Erskine was killed, the Super-Soldier program was continued by Dr. Joseph Reinstein, who in the MCU is a completely separate entity from Dr. Erskine, and reverse engineered the serum in Steve's blood to create his own version. The serum he created eliminates the need for vita-rays and creates a more powerful super-soldier, but also drives subjects insane after a while. Someone volunteered for the experiment and Howard Stark created a shield for him made out of powerful plastic. //The shield is the one seen in Tony Stark's workshop. And the serum is the one given to Blonsky.

Cap's posse came together due to sympathy magic from Thor's posse forming in Asgard at the same time, or vice versa
Both posses include:
 * A Lady of War: Sif, Peggy.
 * A husky gentleman of the ginger persuasion with impressive facial hair: Volstagg, Dugan.
 * A classy, dashing chap: Fandrall, Falsworth.
 * ....Guys who are/look Asian? Hogun, Morita.
 * If you believe Bucky will be back as the Winter Soldier, then guys who started out as the hero's bros and turned evil: Loki/Bucky.

Hydra (or by the time whats left of it) where in volved in summoning Hellboy.
The camera takes a close shot at a Gas Mask Mook when Red Skull explains that he and Hitler share an interest in the occult. The Gas Mask look very similiar to Karl Ruprecht Kroenen'S Gas Mask.

Bucky killed Howard Stark.
After he felt off the train, Bucky was rescued by a Soviet unit and turned over the years into the Winter Soldier. As revenge, some Renegade Russians sent him after Stark, one of the top men at SHIELD, which had played a hand in the end of the Soviet union, to kill him back make his death look like an accident.

Dugan receives the Infinity Formula.
In the 616 comics (mainstream universe), it's stated that the Infinity Formula keeps Nick Fury from aging and it's been implied that Dugan received it, too. So it's possible that he could still work for SHIELD in the MCU if they state this outright, since Fury is no longer a Howling Commando in this 'verse.
 * Also, is it possible that the Infinity Formula could have been derived from whatever HYDRA was testing on Bucky?

Not only did Bucky survive his fall, but he was also on ice for a number of years (possibly continuing into the present) because of Hitler's vendetta against the Russian Front.
Hydra's experiment wasn't to use the Red Skull formula on him, but rather to prepare him as the perfect soldier to fight their neighbors to the East. Part of the experiment was to make a soldier who could survive freezing. They were only in the beta stage, so they managed to make him immune to death by frost, but not to cryopreservation. He's barely stronger than any other non-Super soldier, but he can survive freezing and take a lot of punishment due to the strengthened bonds of his cells and tissues that allow them to survive the crystallization of the water within them.

The movie takes place in an alternate universe of A Matter of Life and Death.
There's the fact that Cap attempting to land the plane in the Arctic looks eerily similar to Peter Carter attempting to escape the burning Lancaster plane in Life and Death. And also how Peggy Carter from CA:TFA looks very much like June from Life and Death, and perhaps Peggy is an alternate gender-flipped version of Peter Carter, who's on the different end of the situation? Consider the fact that both Peggy & Peter are British and share a surname, while we never learn June's (who's an American, by the by...) last name. Who's to say that her surname is "Rogers"?

The english city names written on the flying bombs were just for propaganda purposes, filmed or photographed before flight.
Seemingly obvious enough conclusion to draw, though some reviewers seemed to take issue with that bit. Huh.
 * Actually, American city names are written in exactly the same way in German as English.

The lady from the end IS Sharon, but...
She'll be recast in the sequel. Or if they want to bring back Hayley Atwell, she'll have been just some random SHIELD agent.

The movie takes place in both the Hellboy and Indiana Jones universes
Of course, there's the Red Skull's "Hitler's digging for trinkets in the desert" line, but take into account HYDRA's fascination with the supernatural side of things, and there's the possibility of a small sect within the organization focusing on the rather occult, like drafting demons and various creatures onto their effort. Then again, the pipe dream of seeing Hellboy, Cap, and Indy teaming up to kick Nazi ass is just too amazing to pass up.

Loss of the super serum led to the Weapon X program
Even without the super serum used on Cap, the government wanted to keep making super soldiers. Unfortunately, the scientists weren't able to recreate the original serum and came up with their own procedure. Namely, overlaying or replacing the skeleton with adamantium and introducing the regenerative ability in the subjects who didn't already have it (like Deadpool). Therefore, Cap is in the same universe as the X-Men movies.
 * Contradicted by TIH: they actually did recreate the super soldier serum, they just never were able to work around the psychological side effects.

Arnim Zola helped found SHIELD
After the war, the Government offered him the full Von Beaun deal.
 * Considering the advanced tech that SHIELD has at their disposal, I could easily see Zola being at least an advisor to the group in its early days. His portrayal in the movie (not including the Super-Soldier game) doesn't seem to make him as gleefully villainous as his comic counterpart. It's implied he's only working for HYDRA due to his love for science, so this WMG is a possibility.
 * Kinda-sorta confirmed in The Avengers -- SHIELD has a whole stockpile of old HYDRA gear and at least one of their research goals is to reproduce the technology.

Red Skull ended up as a joke in Asgard
As any Nazi, Red Skull is a racist and white supremacist. Heimdall in the MCU is black. If Red Skull ended up at Bifrost while Loki was around with a recorder, he probably made him a memetic joke in Asgard by making public his reaction.

Sue and Johnny Storm are close relatives of Steve Rodgers.
If the Fantastic Four movies do take place in the Marvel Cinematic Universe, this could explain Steve and Johnny's resemblance.

That waitress who's grateful for Cap saving her in The Avengers will appear in Captain America 2 as a potential love interest or confidant.
Which would present an interesting situation should they have Sharon Carter appear as a supporting character for Cap.

Maria Hill will end up as a love interest for Cap.
Was anybody slightly reminded of Peggy by her competency and general badass-ary? Maybe if she defrosts herself a little.

That kid with the garbage can shield at the end is a young Phil Coulson.
This Tumblr posting gives a pretty damn good theory on possibly why.