Continuity mistake: When at his house, the first crew member Michael kicks with a camera. He puts that camera on the ground, tripod closed and laying down. When the people first walk into the house they switch to a camera view that's up the stairs and you can see that the camera that was laying on the floor is now propped up against the wall.
Continuity mistake: At the party, when someone screams out to turn the volume down, right behind the kid that plays Decker is a blonde haired boy with a red smoking jacket. It then cuts back to inside the Myers' house for a few minutes. When it cuts back to the party that same blonde haired boy just walks in as if he wasn't in there before, asking what they are watching.
Continuity mistake: When it flashes back to how Michael Myers survived the end of H20, we see the paramedic that he subdues and switches places with. That paramedic had a bit of a stomach on him, yet the figure of Michael Myers throughout the rest of H20 after the switch remains the same as the real Myers. [A side note: Halloween H20 WAS intended to be the absolute final film, but popular demand forced a return and obviously they needed a scapegoat excuse to bring Myers back. Still...]
Continuity mistake: When you see Sara driving up the school path on her moped you see a lonely girl sitting on a bench and when it changes to the next shot she is gone.
Continuity mistake: In the scene when Rudy has the last last knife stabbed through him about fifteen centimeters of the blade go through the other side of the door. About fifteen seconds later from the fitted camera view you see Michael open the door and Rudy has a large, thick padding on his back. There is no way the knife could have gone that far through the other side of the door if the padding would have been that thick. (01:04:20)
Continuity mistake: After Deckard receives the e-mail on his computer he writes about three lines below but about five seconds later when you see the computer screen he is just beginning the sentence on the first line. (00:19:55)
Continuity mistake: When the six enter the Myers' house outside you see Sara walk through the doorway and nearly reaching the stairs but about five seconds later she is just entering the doorway. (00:31:25)
Continuity mistake: When Nora is making her coffee from the machine you can see most of the computer screens. If you look at the one with Charlie on it you can see him walk backwards with the tripod leg pointing at him, but in the next shot,when you see the screen close up, he is kneeling down, Michael Myers catches his attention and then he stands up. (00:28:30)
Continuity mistake: At the start of the film after the crazy guy is pushed out of the room Sara says, 'I just need to send a quick e-mail.', and when you see her type it in there is a really long word or sentence on the screen but in the next shot close up there is just the word 'Deckard'. (00:19:40)
Continuity mistake: When you see Sara riding her moped up on the road on the way to the meeting with Freddy the sky is blue and dark but when you see her enter the door to the room you can see in the background sunlight coming in from the windows onto the walls. (00:20:50)