Continuity mistake: When Ashley moves in with her two friends she breaks their bathroom mirror with a hairdryer. Later on in the movie, in the scene where her two friends are giving her a pep talk about luck, we see the same bathroom mirror in the background, which is now perfectly fine. Right after that, Ashley goes into the bathroom and looks at herself in the mirror, which has suddenly gone back to being broken.
Continuity mistake: Towards the end of the film, Mattie hands Jenna the dream house he made for her 13th birthday. There is hardly any "wishing dust" on the roof. However, when she goes outside and sits on her front porch, there is plenty of wishing dust all over the roof of the toy house now.
Factual error: When Luke is playing video games in the camp he is using a Playstation controller, however when he pauses the game it shows a message telling him to push the 'B' button. 'B' buttons appear on Xbox games consoles rather than Playstations.
Revealing mistake: In the last third of the film just after the announcement that Kong is coming, a native jumps out of his hut, loses his balance and falls by a chicken coop. His wig comes off and gets caught on the fence.
Continuity mistake: When Wednesday and Pugsley are playing with the guillotine, Wednesday has a scroll in her hands, which she then rolls up. The shot changes and you can still see the rolled up scroll in her hands. However, the shot then changes again and you can now see Wednesday rolling up the already rolled up scroll.
Continuity mistake: In the scene where Eddie Murphy is going into the crypt, he takes one of the lit torches. While they are trying to escape the skeletons, the door to the crypt closes and locks. When they show the shot of his son outside, you see two torches again. When he gets the doors open and they leave, you see one.
Continuity mistake: There is a scene in which a ghost shoots harpoons through the back door of the Mystery Machine. In the next shot, the harpoons are gone, and when the van gets back into the city you see a shot of the back and there is no damage whatsoever. (01:03:20)
Continuity mistake: When he sees Meg in the river of death, he reaches down and touches it. Then, when he jumps in, he makes a dive of at least 50 feet. (01:11:25)
Continuity mistake: When Mel tries on the pantyhose, the hole in the left leg changes from large on the outside of his leg, to small with a run on the outside of his leg to large on the inside of his leg. (00:25:45)
Continuity mistake: In the scene where Joe Gideon is helping his daughter with dance exercises and realises that it is time to put Michelle in a cab, he carries her out of the rehearsal studio with her facing forward and her legs wrapped around his back. They turn a corner to go outside and she magically is facing him arms around his neck and legs wrapped the other way around his waist. Also Michelle suddenly grows a yellow rain jacket. There is no time lapse in the dialog which would explain this turn.
Visible crew/equipment: When Francesco and 'she' are in the cemetery together and the little blue flame-beings gather around to watch them, you can see the wires they're suspended on several times. This is most apparent when Francesco sees the first one (moments before seeing 'she' at the fountain) and also just before they are all frightened away. (00:17:30 - 00:20:40)