Nitro Express

Nitroglycerine is an unstable substance and handling it is a nerve-wracking experience. What better way to ramp up the tension level in a story than to have the protagonists be forced to transport some a long distance through a hostile environment?

This trope describes a plot where the heroes are required to move nitroglycerine (or some other unstable, highly explosive substance) across bad terrain (rough ground, winding roads, etc). Note this needs to be a substantial journey. Just moving it from one room to another wouldn't count.

Examples of Nitro Express include:

Comic Books

Lucky Luke had a comic devoted to this, it's just too bad that the Daltons decide to hijack the train, not knowing what's on it, and run close to blowing themselves to kingdome come.

Film

Danger Patrol, a 1937 film about 'soup handlers' hauling nitro around the oilfields.
The Wages of Fear (Le Salaire de la peur), a classic 1953 French film. When a South American oil well owned by an American company catches fire, the company hires four European men, down on their luck, to drive two trucks over mountain dirt roads, carrying the nitroglycerine needed to extinguish the fire.
- Remade as Violent Road (aka Hell's Highway) in 1958, and Sorcerer in 1977.
Chill Factor: A 1999 movie that's perfectly described in this trope on ice.
In the film Vertical Limit, the characters must transport nitroglycerin up K2 as part of a rescue mission.
The Legend of Zorro: The hero and the villain have a swordfight on top of a train loaded with the stuff.
Four Lions: Five wannabe mujahadeen have to transport home-made explosives from one "secure" location to another (a squat to an allotment shed). They start off driving very slowly and carefully, but the car breaks down. They then have to do a very silly run the rest of the way (to avoid jarring the explosives and setting them off). A deleted scene includes a chase sequence, while still carrying them.One guy trips over a sheep, and blows himself sky high. Judging by the disclaimer at the end, said sheep was killed by the special effects pyrotechnics. Note: ovinophiles and other animal lovers may wish not to view the spoilered section.
In the end of The Giant Gila Monster, the protagonist drives a hot-rod across uneven ground towards the Gila Monster, with the passenger seat full of unstable nitro.
Unstoppable is about a Runaway Train with eight tank cars filled with explosives.
At the beginning of the Wild Wild West film, Captain Jim West jumps on a wagon carrying cases of the stuff (with only hay for padding) for a renegade regiment of the former Confederacy.

Jim West: This is not the way you transport nitro!!!

Live Action TV

Mission: Impossible: "Nitro"
The MacGyver episode "Hellfire". Mac has to transport old, sweating dynamite cross-country from an abandoned mine to extinguish an oilwell fire on a friend's claim.
There was an episode of The A-Team where they were transporting dynamite - which is not normally volitile until/unless it has a blasting cap attached - but it was really really hot and as a result the sticks of dynamite were sweating nitroglycerine.
The first episode of Gemini Man centers on The Hero protecting an inventor and his super fuel additive from the minions of the "international oil cartel". However, the inventor has already sold out to the oil companies and plans on Faking the Dead using the additive's explosive properties (a large beakerful supposedly being enough to take out a small town). As Mike and the Bots point out, the actual explosion wouldn't destroy a town ("Maybe singe a bed-and-breakfast", Crow remarks).
Played with in an episode of The Andy Griffith Show, where two yokels who accidentally pick up a container of nitroglycerin (somehow mistaking it for fertilizer) manhandle it for the entire episode. It is only when it is dropped down a well that it finally explodes.
On Lost the protagonists find dynamite in the wreck of an old ship and need to transport it through the jungle to blast their way through an obstacle. It is very old and sweating nitroglycerin. They use it on multiple occasions throughout the series and two times one them is accidentally killed when it blows up
Parodied in Beakman's World, where Lester bringing a bottle of the stuff from the "REALLY DANGEROUS STUFF" cabinet to the couch is portrayed like this.
An episode of Grey's Anatomy had the surgeons trying to remove a bomb from inside a man's chest before a disposal team could deactivate it, and naturally included a scene where they had to push the gurney very slowly down a corridor.
- After removing the bomb, the bomb squad guy is slowly carrying it to the disposal unit. The bomb goes off, vaporizing him and nearly killing Meredith.

Music

Referenced in Convoy by C.W.McCall. The convoy's unofficial leader, Rubber Duck, asks a chartreuse minibus driven by 'eleven long-haired friends of Jesus' (that is, Hippies) to put their bus in behind a 'suicide jockey'. "Yeah, he's hauling dynamite, and he needs all the help he can get!" Considering that the convoy is, by then, doing 98 MpH and crashing through roadblocks and the like, his worries are understandable - under those conditions, even dynamite (which was specifically designed to be a more stable alternative to nitro) can't be considered particularly safe.

Video Games

Blast Corps is about tearing up stuff to clear the path for a truck carrying two defective nukes that will blow up with as much as a little jolt.
The remake of Resident Evil 1 has you walk slowly with explosives, or you get a Game Over.
Spyro the Dragon titles have several missions which involve Spyro clearing a path for a character who has lit a bomb and must run it to a destination. Expect much restarting while you learn the path the characters in question take to their destination.
Some missions in the Grand Theft Auto series have you drive a vehicle carrying explosives that will blow if you bump it too much.
Similar to the above, in one mission of Driver, you must deliver a crate of unstable explosives in a pickup truck across the hills of San Francisco.
One Escort Mission in Quake 4 has a demolitions expert carrying explosives that will "take out half the mountain" if set off.
The bomb disposal driving mission in Die Hard Trilogy 2. One bump, you get a warning. Two bumps, it explodes.
Castlevania (Nintendo 64) has a part in the game where you have to carry Nitro. If you run, jump or fall at any time while carrying it you have to start ALL OVER AGAIN!

Western Animation

Wild West Cowboys of Moo Mesa had an episode featuring this.

Real Life

In case you wonder how the sane people handle this in sane conditions, it's the same as with medical nitroglycerine: it's either absorbed on solid matter (the whole point of making dynamite), or diluted with alcohol enough that the solution won't explode from almost anything you can do to it. The downside is that conditions that cause separation of those substances are less than exotic (dynamite may "sweat" from prolonged heating, for one), so such things need proper storage to stay safe, or you are dealing with "temperamental" liquid TNG again, perhaps when not expecting this.
During the construction of the Canadian Pacific Railway, this is the job that tends to get fobbed off to the Chinese migrant workers, Loony Tunes-style slapstick does not ensue.
In Seven Pillars of Wisdom, T. E. Lawrence describes hauling blasting gelatine and guncotton around the Judean desert on camels and in rather rickety cars. Remarkably, nothing too terrible happens.