Trapped in Containment

So the Big Bad and his minions have stormed the secret laboratory and captured the MacGuffin. But we really need to show the audience what is at stake here without having the villain pass through the Moral Event Horizon. So one of the Mooks will be fumbling around with a vial of the stuff, it will fall to the floor, shatter, and everybody except said Mook will escape in time. The door will seal, and the Mook is left to his horrible fate as the rest of his compatriots look on sympathetically. He has been Trapped In Containment.

It needn't be a chemical weapon -- it could be as simple as someone trapped behind a door as it fills up with water -- although it usually is.

Note the odds are 99% that someone will attempt a Indy Hat Roll. Naturally, this trope doesn't count for those who succeed.

Anime and Manga

 * In Full Metal Panic? Fumoffu, one of the students mistakes a container of a biological weapon Sousuke had brought to school (he had gotten it by mistake -- he had ordered a sniper rifle scope) for a drinks container and accidentally opens it. Hilarity Ensues as Sousuke tries to keep it from spreading outside the classroom and traps the entire class in containment.

Comics

 * The origin story for Doctor Manhattan involves this.

Film

 * The opening scene from The Rock involves a Mook being trapped as some VX nerve gas does some funky stuff to him that definitely doesn't happen in real life. (at least, not with VX. Mustard gas, on the other hand...)
 * James Bond accidentally (or not) causes this to happen to a couple of scientists working for the Big Bad in Moonraker. Whether or not he cares is a different issue.
 * In Xx X, the Vin Diesel movie, the Big Bad seals the scientists who created the stuff in the room, then watches on as it kills them all.
 * This trope is the reason Spock makes a Heroic Sacrifice in the second Star Trek movie.
 * In Species, they're tooling around with the alien DNA about halfway through the movie. Hilarity Ensues.
 * The dissection scene from Independence Day almost counts: The onlookers arrive after the damage is already done, and the threat from the contained entity is psychic, not biological.
 * This also plays into many submarine movies, with a compartment flooding, and characters having to make one of two choices: Do we close the watertight doors, saving the ship but killing the men in that compartment? or do we stay and try to stop the flooding, knowing that they're going to close the watertight doors and if we don't succeed we'll drown or do we get out without trying to stop the water?
 * Examples: when the rig is flooding in The Abyss.
 * Also Crimson Tide
 * Happens in the beginning of Resident Evil. A Villain deliberately breaks a container and releases the T-Virus. Later, when the Red Queen seals the room several researchers are trapped inside as the room fills with water for some reason.
 * It was from the fire control sprinklers.
 * In the third Resident Evil movie the bad guy locks two assistant scientists in with a zombie when it breaks free of its restraints.
 * The Andromeda Strain example below also occurs in the 1971 movie version.
 * The League of Extraordinary Gentlemen. When the Nautilus is sinking, Nemo orders that the engine room be sealed off so the water doesn't flood the rest of the ship, condemning the crew trapped in it to death by drowning.
 * In the remake of The Day the Earth Stood Still, a government agent does this to a scientist who is contaminated while investigating a caged alien artifact. Naturally he is less pleased when the contamination starts eating through the windows and his room is the next to be sealed and sacrificed.

Literature

 * Much of Michael Crichton's The Andromeda Strain is centered on this type of set-up. Near the end, one of the scientists is stuck within the contaminated area due to a failure of the lab's airtight seal.

Live Action TV

 * Season three of 24 has this happen on a larger scale involving some gas and a hotel full of people. The writers knew that actual procedure was to remove people from the building, but limited budget and a desire for increased drama meant they left them in there.
 * This is played for comedy in the very first scene of The Middleman.
 * This is done a couple of times in Stargate SG-1.
 * In Look Around You, the danger of the Helvetica Scenario is illustrated by a scene of a masked literally faceless scientist pounding futilely on a glass window while another stands outside taking notes.
 * The Lone Gunmen got themselves deliberately Trapped in Containment when they made their Heroic Sacrifice at the end of The X-Files.
 * Another episode had WW 2 submariners locked in with their captain who was infected with the black oil.
 * Done in the pilot miniseries of Battlestar Galactica Reimagined. Colonel Tigh orders the hatches to the flight deck sealed to contain a fire, as the Galactica is under heavy Cylon attack. Unfortunately, there are 85 crewmen trapped inside. Chief Tyrol nearly has a Heroic BSOD trying to convince Tigh to let him make a rescue attempt, and then watching Tigh activate each hatch lock in turn.
 * Not only did he have to seal them inside to prevent the fire from spreading. He also had to dump the air from that part of the ship into space to extinguish the fires.
 * In an episode of MacGyver, a scientist creates a chemical for maturing plants. When her dog knocks over the vial, she is trapped with it and ages to death.
 * In the Doctor Who episode "Planet of the Daleks", a Spiridon slave opens up a deadly toxin the Daleks have been developing, leaving them trapped. Unusual in that the trapped Daleks are actually immune to the virus - but they still can't open the door because they are the only ones who are.
 * Star Trek Voyager. In the "Year of Hell" two-parter the EMH is forced to shut the hatch on two crewmen because the corridor is about to vent open to space.
 * In the season 2 episode of The Mentalist called "Code Red", a bioweapons researcher finds out that one of the vials with a super-virus has spilled. She immediately locks down the containment room with her inside and calls CBI to get them started on looking for her murderer, knowing she only has hours to live.
 * An episode of The Outer Limits has a scientist accidentally create what appears to be a cure-all for anything ailing a person (while working on a safe knockout gas). This happens twice. First, his research assistant punches the door in the lab after injecting himself with some of the compound, causing the containment system to activate in the presense of chemicals in the air. He is incinerated, as his boss refuses to open the door. The second time is caused intentionally by the scientist's brother, who activates the containment system, but the scientist and his girlfriend manage to escape just before they are incinerated.
 * In a season 4 episode of Primeval, Philip Burton has Connor run a scan on the entire ARC for any foreign organisms. He then walks into the creature pen and sees Rex out of his cage. Before he can do anything, the scan detects Rex and locks down the entire facility. Burton is trapped in the pen with the air being sucked out. Luckily, Connor realizes that Burton built his security system on Connor's own software, for which Connor has a backdoor.
 * In an episode of Criminal Minds, Reid becomes locked in a home biological laboratory when he notices a broken vial of weapons grade anthrax on the ground. However, he locks the doors himself as a way to save Morgan from the same fate. Luckily, they discover the antidote to the strain in time to save him.

Video Games

 * In Rainbow Six: Vegas 2, you're going in to rescue hostages from a building, then the terrorists lock all the doors and put gas into the ventilation system. You are too late, and stand outside the door hearing screams and dying as a bit of the gas floats out through the cracks in the door. Luckily, you have gas masks on.
 * In Fallout 3, a radiation containment room containing the master controls at Project Purity provides an opportunity for all kinds of hijinx. First, after he deliberately floods the room with radiation, trying to . After that, you return to the room and have to choose whether to  to reset the purifier to a safe level, or let Star Paladin Cross do it instead. You can Take a Third Option and have.
 * The Broken Steel DLC lets you
 * A delightfully cruel level in Psi Ops the Mindgate Conspiracy. In it there were three gas chambers that seal once you enter the room. Bullets do no damage, and only by using telekinesis can you break the glass and not die of poisoning. The fun part came in with the fact that you would either get stuck with a scientist inside, in which case you could smash him against the glass to break it, or there would be a taunting faceless goon outside you could use to crack it. And if you're fast enough, you can trigger the doors and skip out while remaining outside, leaving the poor science mooks inside to slowly die.
 * The rather weak game Spy Fiction justified this: The villain trapped the scientist in there to get rid of him while demonstrating what the virus, Lahder, could do.
 * Subverted in several of the Resident Evil games, where you're the one locked in with the vicious monster. Occasionally it's because the Big Bad is doing it on purpose, and sometimes it's an automatic lockdown procedure that goes off when something big wakes up in the room. In either case, the doors generally open back up once you kill whatever it is.
 * Dead Space has the same happen occasionally. Whenever there's any kind of quarantine measure going on, you can be certain a monster will break in and fight you, with the quarantine ending as soon as you dismember the creature.
 * In Mission Critical, you find a diary of a traitor onboard the ship, who recounts a memory from his childhood of his parents, scientists specializing in nanotechnology. The parents were working with a prototype nanite colony designed to break down waste. However, the nanites break free, and the parents are stuck in containment as they are eaten alive in front of their children. This is described as the reason for the character's Face Heel Turn, as he came to realize the evils of technology.
 * Two mooks do this to themselves in 'Perfect Dark when they trigger the nerve gas defense system in Area 51 - and lock themselves in the lab by doing so.

Web Original

 * College Humor has this commerical.

Western Animation

 * In The Spectacular Spider-Man, this is featured as a part of Doctor Octopus' origin story.