Revealing mistake: When Henry's mom is pushed off the cliff her cable is visible.
Plot hole: After Max and Allison rescue Dani from the witches, Max is driving his parents' car. Winifred flies up along side of them and asks Max to show her his driver's permit. How would she know about driving permits, since she's been dead for 300 years?
Suggested correction: There is a lot the movie doesn't show us about who they've passed and what they heard all evening. One example being we don't know everything the bus driver said to them. It's perfectly reasonable they heard somebody make reference to a driver's permit and the movie did not show us this conversation deeming it invalid to the plot.
Not referring to a learner's permit. She would have known what it means. She's emulating a cop pulling him over. She would have to know what that means...and know the difference between a license and a learners permit. Enough to find it funny and relevant to the situation.
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.
Other mistake: In the scene at the beginning where Phil eats Jason's Heart, you'll notice that he screams like a monster for a bit. Don't you think that the two security guards would easily hear the screaming and intervene, being that they're in the very next room? (00:13:40)
Revealing mistake: While in the convenience store, watch the arcade screen the punks are playing, they are getting very excited about the game, however anyone who has played Street Fighter 2 will notice that they are merely looking at the demo version and even the words "insert coins" are displayed on the screen.
Continuity mistake: After Nathan pours the gasoline and throws the match in the well, we see a canister and shotgun sitting by well. But when the well explodes, they've disappeared. (01:23:50)
Revealing mistake: At the end of the movie with Matt Cordell (Maniac Cop) chasing after the detective in a police car while being set on fire, you can see the safety goggles under his mask in several of the changing shots in this stunt scene.
Continuity mistake: In the prosecuting attorney's speech in the first courtroom scene, the judge's house of cards is no more than 2 levels high (a base level with a peak) [0:2:20]. In the close-up shot of the judge, the house of cards changes to 3 levels high (2 base levels and a peak)[0:2:35]. When the scene focuses back on the prosecuting attorney, the house is back to two levels of height[0:2:39]. (00:02:20)
Continuity mistake: In the scene where Gard telepathically fights an alien, you see his nose bleeding. Then the alien explodes, and in the next shot of Gard's face, the blood under his nose has vanished, only to return in the next shot of his face.
Revealing mistake: Dr. Piper gets her left ring finger cut off by a Totem, yet while she is running, the finger has reappeared. (00:09:00)
Visible crew/equipment: In the scene where Julian Sands confronts Paula Marshall on the holy druid site, there is a shot where he pushes a Stonehenge-like boulder over in an attempt to crush Paula Marshall. As the boulder topples over, behind it you can see the heads of the crew members who are doing the actual pushing. (01:24:25)
Plot hole: In the scene in the hotel, David sees the victim's head on the floor after the killer left. Later when David is in a hospital bed he is watching TV and the reporter claims that all the heads were in Judd's car. The killer would have had to have gone back into the hotel room to get the head of that victim after David saw it. She would have put it in her bag right away if she was saving them all. The bag was even left behind. (01:12:30 - 01:25:00)
Factual error: Detective Beck's daughter states that she had not seen her father for several years. That he lived as a hermit and did not let her in. Then why when she goes with the good alien to where her father used to live, she has the key to get in?
Continuity mistake: Julia is apparently being helpful towards the stranger at the door. She is taking notes as he says his name and auto club card number. She is casting a visible shadow on the door, entirely gone in the close-up of the door itself. (00:08:15)