Revealing mistake: Obvious stunt man for Carrie Snodgrass due to having brown hair while she's a dark blonde when hanging from an axe handle near the end of the movie. (01:35:09)
Revealing mistake: When Norman drives Dukes car into the pond, it's obvious no one is in it.
Revealing mistake: In the taxi scene Ferris' dad is reading a newspaper. On the front page is an article with the headline "Community rallies around sick youth." As the camera zooms in it's a fake headline to a real news article. The news article begins, "A Chicago policeman killed himself today after he... a Park Ridge office and... workers with a... revolver as he searched for his estranged wife who was hidden beneath a desk by a fellow worker".
Revealing mistake: In the Director's Cut ending when Audrey II eats Seymour, it spits out his glasses, and they land in front of the camera. They pulled this off by having a pair of glasses inside the plant's mouth that would be yanked out by a string, and another pair of glasses would be dropped in front of the camera. However, the first pair gets caught in the teeth and fall back inside the mouth, but the other pair lands on the ground anyway.
Revealing mistake: The chairman parks his car in front of Bel Fuse Ltd. And goes upstairs. His car explodes, but does it in front of a different building, probably switching to a stage building front; the metal doors don't have vents anymore and there are visible join lines in the asphalt and the cement. (00:15:10 - 00:15:40)
Revealing mistake: When the bully's held up by Sam wires can be faintly seen.
Revealing mistake: The scene in the locker room when the bullies are dunking Marty in the toilet. Marty's "body" is a fake prop used - on the naked body mysteriously there is no penis or testicles. In addition to this, despite being turned completely upside down, Marty does not struggle in the slightest as he would in real life - he does not struggle at all exactly because it is a prop body being used.
Revealing mistake: During "Never Say Never" Henri instructs Chantal to fly Fievel to immigration where he should be able to find his family. At one point during this shot, Henri's right wing casts no shadow on the Statue of Liberty - only an outline of the wing's shadow is visible. (00:23:25)