Revealing mistake: In the scene where Ronnie visits Brundlefly for the second time we see Brundlefly walking on the ceiling and wall, however his shirt doesn't remain consistent with gravity. This is especially obvious when he pulls his shirt up to show Ronnie his new tumor and then places it back down. The shirt appears to be being pulled up to towards the sky from Ronnie's perspective. (01:07:30)
Revealing mistake: When Number 5 is leading Number 3 into the toilet and moves at the last minute, you see Number 5 falling over, but in the next scene, he's perfectly fine.
Revealing mistake: When Jackie jumps on the hot air balloon, he is supposed to be REALLY high in the air. Still you can see tops of trees on the lower right corner of the screen.
Revealing mistake: In the car chase scene where the cop is after Roland, you can see that there is no key in the ignition of the cop's car.
Revealing mistake: After the bounty hunter, who changes three times throughout the movie, changes into the Reverend, he is in front of someone else who is a stand-in for the real Reverend but is obviously not.
Revealing mistake: When Lardass pukes on the guy to the left of him, he moves his head prematurely, and you can see that the vomit is coming out of a jet (hose) positioned behind his head. (00:46:30)
Revealing mistake: At the beginning, when Ivan and the two New York businessmen approach the school, the three are seen through a window from inside the school. If you pay close attention to the reflection of the students in the window, you can see that they are in no way doing anything related to what is being heard inside the school. After the class is dismissed and starts to leave, we see Ivan and the two businessmen begin to enter the school, and if you look in the window, the class is still going hard. (00:03:00)
Revealing mistake: When Sarah discovers Toby has gone from his cot, Goblins start moving about in her fathers room. The second goblin we see laughs, and jumps down from the top of her fathers four poster bed. As the goblin does this, you can see the shadow of a boom mic bob down onto the material that drapes from each poster of the bed. (00:11:05)
Revealing mistake: It is obvious a dummy was used when Steve is thrown from his easy chair into the kitchen cabinet.
Revealing mistake: Later into the film Roger realises that his aunt's paintings hold some significance to the whereabouts of his missing son. He removes a cloth from the top left of a painting revealing an image of his son trapped in his bathroom cabinet. Note the cabinet door is the wrong way round to the one in his bathroom.
Revealing mistake: When Jim hits the brakes in his stolen patrol car, the two pursuing police cars turn and flip over and over. As they roll, the 'roll cannon' is visible on the underside of one of the cars (a round steel tube in a hole in the floor) and at left, the two cannon slugs from both cars bounce down the road. This device fires the slug downward, and the force behind it lifts the car when the slug hits the road, launching the car over.