Revealing mistake: At the end of the movie, when François is waiting for Christine's call, he moves his hand just before the phone rings, as if somebody gave him a signal.
Revealing mistake: When Puffy the dog bites Ted and pulls him along, Ted digs his fingernails into the floor, they scrape along, making marks. If you look very closely you can see faint pre-made marks made in the floor, where he drags his nails along. (01:28:45)
Revealing mistake: As Ted is being burnt by the fire, you can see his body trapped underneath the debris. In a side shot of Ted it is very obviously a stunt dummy as the left arm and head stay completely still and the arm remains completely stiff despite hearing screams and shouts from the pain.
Revealing mistake: When one of the bad guys is being dragged around by the monsters and thrown against pipes and walls and such, in wide shots you can see there is no monster really pulling him, and from the stiffness and position of his body, he is likely on some sort of device to swing him around.
Revealing mistake: When Andy was found dead from an overdose watch as the camera zooms out from him, he blinks. (00:34:10)
Revealing mistake: When Chris is being hanged you can see the back of his jacket being pulled up from the harness.
Revealing mistake: When Finn draws a fish at the beginning of the film you see a dent already in the paper at the spot where he draws the eye. (00:03:10)
Revealing mistake: The iron mark on Roy's shirt is obviously painted on. (01:16:20)
Revealing mistake: When Jackie falls from the helicopter, in the close-up of him falling towards the trees, you can see a wire coming from Jackie's' left; using slo-mo helps. (The use of slow motion is permitted if things such as crew or equipment are visible.)
Revealing mistake: As a homage to the original; when Norman carries Marion's dead body, wrapped in the shower curtain to the car, you can see her bra strap through the curtain.
Revealing mistake: When Suzi Amis is hanging from Howie Long's leg in the parachute scene, you can see that the stuntman is not holding on to his leg, but some kind of wire harness.
Revealing mistake: At the beginning of the scene where the Reverend sells the guns to Mel, Bobby is walking outside and it is rainy and stormy. But once he enters the motel room there is sunlight streaming through the windows. Then, in the next scene when he is outside with Rosie, it's stormy again. (00:34:00)
Revealing mistake: At the beginning of the movie, the little brother of Christy found the small soldiers at the rear of the shop. One of them shoots something at him, but he blinks before it is shot. (00:16:35)
Revealing mistake: In the opening credits, there's a shot of the first film where Jacquouille takes the jewels of the dead Duke. The "dead" man moves.
Revealing mistake: When Hobbes is searching for information about Milano, he types his search into the webcrawler search engine and it takes him straight to the front page of the newspaper that is reporting on the events he is searching for. With the search terms he used there is no way he would get that result. You may argue that all the boring bits of websearching were cut, but for his second search he goes back to the web search instead of the newspaper's own search to get the next year's article. (00:22:00)
Revealing mistake: You can tell all shots in the parallel world where there is writing visible are simply regular shots being reversed because Molly Ringwald's watch and ring, which she wears on her left arm and hand, suddenly are on her right arm and hand. Especially obvious in the scene where she goes over work papers with Sandy.
Revealing mistake: Both times Chris Kattan "breaks" the car window, you can tell that it breaks on its own.
Revealing mistake: In all the scenes where Tum Tum kicks the ninjas, you can tell it is a fake leg in the closeups.
Revealing mistake: During the scene in which the small group of GIs, led by the young go-getter officer played by John Cusack, attack the Japanese hilltop bunkers, they seemed to be equipped with magic bullets. The American soldiers are firing wildly in all directions but seem to drop an enemy soldier with every shot. In some shots, the GI's rifles are not pointing even near where the Japanese soldiers are but the latter obligingly fall dead nonetheless.
Revealing mistake: When Dolittle is called in the middle of the night to give Miss Parker her injection, watch the injection: When Dolittle pulls the injection equipment away from her fat leg, the needle is gone.