- Stuff like this has been known to happen during a play. Even professionally trained actors can probably tell you of a story where something either went wrong during the rehearsals, performances, or even Opening Night! Generally it's best to just improvise.
- Sometimes it can be amusing, such as Peter Pan destroying the Darlings' bedroom and Jane suddenly flying out of bed, the latter of which seems to happen a bit more than you think.
- The first story is a Crowning Moment of Awesome in abject special-effect failure.
- The flower will not stay in Elphaba's hair.
- Not to fear little children, I will hel-"
- In A Very Potter Sequel, Joey Richter (as Ron) fails to take down a Taylor Lautner poster from Umbridge's office (It Makes Sense in Context) while switching scenes. He tries to play it off by saying it was held on by magic, and in the next scene "They're all over the school!" Twist? It was done on purpose as they needed a reason to have a Taylor Lautner poster in both Umbridge's office and the room they end up in. They couldn't think of an In-Universe reason so they decided to make it seem like a quickly-improvised mishap.
- Referenced in The Adventures of Baron Munchausen, where Sally has to badger the stage crew to start the ocean wave effects.
- The Screen-to-Stage Adaptation of Disney's Beauty and the Beast has been one of the most frequently-produced shows by amateur theatre companies, high schools, etc. since the Turn of the Millennium. Many of these productions have utterly failed to produce convincing Beast costumes/makeups for their leading actors, and photos of these failures are showcased on the Tumblr page Low Budget Beasts.
- In Nerds, Bill Gates threatens Steve Jobs with a plastic lightsaber, and makes the sound effects by buzzing his lips. Jobs mocks the lightsaber and calls it an obvious fake. So Gates cuts off the clown's arm with it.
- Spider-Man: Turn Off the Dark had a first preview that didn't go so well.
- Into the Woods failure.
- There's a Tumblr page similar to the one above dedicated to Low Budget Milky Whites.
Special Effect Failure / Theatre