1632/Funny

Lots in the series, and especially prevalent in the comedy of errors integral to the plots of The Galileo Affair and The Bavarian Crisis. One of the more specific example is Tom Stone who, when tasked with making paper money due to his knowledge in making waterproof dyes, promptly put Johnny Cash on the 20-dollar bill.
- Pictures for one dollar bills include male deer (a buck), fivers have a pair of hands kneading dough, tens have a loaf of bread. Get it?
The Baltic War has Melissa Mailey freaking out after Harry Lefferts has bombs planted on several famous London landmarks like the London Bridge and the Globe Theatre. She's further enraged when Harry dismisses his bombing of the Globe Theatre with a nonchalant "Jeez, Ms. Mailey, ease up some, willya? It ain't like we're talkin' about Grauman's Chinese theater in Hollywood, y'know."
All in all they do quite a number on invaluable historical landmarks. In 1632 they drive a small Spanish army into a nearby castle, then napalm it the next day. Passing mention is made that the castle might be important, but the concern is dismissed. That castle? A UNESCO World Heritage Site with "lasting and universal significance". Considering it attained that listing in 1999, it seems probable that its significance was precisely why it got destroyed in a book published in 2000.
Most of the short story "When the Chips are Down," featuring the four Dungeons and Dragons nerds trying to cook potato chips for the whole town in time for Christmas.
The entirety of the short story "On the Matter of D'Artagnan", in which Cardinal Richelieu tries to locate and gain the loyalty of the hypothetical historical person Dumas based D'Artagnan on. Complete with Richelieu staring at the pictures on the videocassette boxes of two different movie adaptations of The Three Musketeers, musing on if he likes how Charlton Heston or Tim Curry portrayed him better. (Note that he has to judge those movies by their covers, since he doesn't have the machines to play them.)
Back again to The Baltic War: "Who ordered this?"
From The Grantville Gazette, the origin of the Sewing Circle's mutual fund (amusingly, titled "Other People's Money").
In The Bavarian Crisis, "the prince formerly known as the Cardinal-Infante" has the idea for a bold action that will make great propaganda for his new regime. His advisors are aghast, since it involves him risking his life in one of the still-somewhat-crude airplanes. He points out, "Just think of the songs. The poems. The Harlequin Romances." (They're still aghast.)
In the first book, the single casualty on the Grantville side to the Croat attack on the town was a woman injured when a black-velvet portrait of Elvis was shot off the wall and fell on her. The Ring of Fire short story "Between the Armies" reveals that a downtimer, Monsignor Giulio Mazarini, was in the room at the time. Not knowing better, he mistook the velvet Elvis painting for a religious icon and asked, "What saint is this?"
In "Diving Belle" from Ring of Fire II, the story of the church bells of Delsbo.
Eddie Cantrell getting drafted in "In the Navy".
From 1634: The Baltic War

Jesse: No, I've got plenty of other things to attend to. And participating in another argument over machine guns ranks somewhere below getting a colonoscopy, in my book.
Torstensson: What is a colonoscopy? And how soon could we have one deployed against the Ostenders?

- After learning what a colonoscopy is, Torstensson wonders if he could use it, not against the enemy, but to discipline his own officers. Squeal like a pig!
In the first novel, the D&D boys gush about Frank Jackson's tactical planning of an imminent battle and name drop The Duke of Wellington, leading to this exchange:

Frank Jackson (gruff tone): So who the hell is Wellington?
<Beat>
Jeff Higgins (appalled): He's the guy they named your favorite boots after.
Frank Jackson (now impressed): Oh, him. Good man! Whoever he was.

In the first Grantville Gazette, "The Rudolstadt Colloquy", Secretary of State Ed Piazza is attending the colloquy, bored out of his mind and doodling in the margins of his Concordia Triglotta with a pencil when he meets Leopold Cavriani when he sees the latter was bored out of his mind and doodling in the margin in pen.
In 1632, when some of the mercenaries are put in WANTED-DEAD and advised to leave American territories before July 5, the mercenaries' commander complains about the fact that the "American territories" part is unclear. Mike Stearns just stares at the commander. A few months later, the commander has found a job. In Russia. He figures that it would be far enough.
In 1636: The Saxon Uprising, as the authority and legitimacy of Axel Oxenstierna is slowly eroded, and he loses the support of the people, we occasionally cut to a group of Pomeranian fishermen commenting on events. In the beginning, they are all in support of Axel. The second time we see them, they say they should have voted for Stearns, not Wettin. The third time, they all claim they actually voted for Stearns, prompting the one skeptic in the room to comment that within a year, it will seem to have been magic how Wettin got elected, 'seeing as how no one seemed to have voted for him'. The final time we meet them, only one person in their village, an old widow, claims to have voted for Wettin - they promptly remark that Stearns shouldn't have given women the vote, and that they almost didn't vote for him because of that.
"The Ram Rebellion" has Brillo, an unusually intelligent ram with terrible wool who becomes an in-universe Memetic Badass and Memetic Molester through broadsheet stories about his supposed exploits.
At two different points in 1635: A Parcel of Rogues, relatives of Darryl McCarthy comment that since he's too far away for them to give him advice, they'll just have to hope Darryl knows what he's doing. Both times, another family member responds, "You do realize how crazy that sounds?"
From "The Red-Headed League" by Virginia DeMarce, when Marc Cavriani and Colonel Raudegen visit London:

"Early March is said not to be the most salubrious season in England," Raudegen remarked mildly.
"What is?"
"Someone told me once that it was August 23, if I recall correctly. But it may have been July 26."

Rising politician Constantin Ableidinger has a tendency to interrupt another speaker for clarification without waiting to see if the other would've given more details without being prompted. Eventually, one of his colleagues proposes that the next time he does this, everyone else in the room drown him out with a chant of "CONSTANTIN, BE QUIET! CONSTANTIN, BE QUIET! LET REBECCA FINISH!" Ableidinger has a good sense of humor about this, and even laughs — loudly and with obvious sincerity — the second time he's shouted down.