Continuity mistake: The blonde girl has very thick black roots. She is decapitated. When Michael throws her head down the stairs, she is perfectly blonde, no black roots.
Revealing mistake: When Jen has her head cut off, the cord to the camera would be severed too, yet it is still broadcasting when her decapitated head is lying at the bottom of the stairs.
Continuity mistake: When Michael Myers is walking towards his sister's room at the mental ward, the camera shot is behind him, as he holds his knife by his side. The camera angle changes to his front, and now the blade is at his front.
Audio problem: When Harold is talking about Michael's past, his lips are not moving as he says that Michael killed three nurses and a paramedic.
Revealing mistake: When you see Freddy's car parked outside the Myers' house when the trunk is open,you can easily tell that the background is artificially created and there is a wall at the side with painted clouds. (00:27:20)
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.
Revealing mistake: After the hallway camera cuts out, it eventually comes back on the computer screen that Deckard is looking at. If you look at the landing and the stairway, the picture is reversed. (00:40:05)
Continuity mistake: When Freddy arrives at the Myers' house the sliding door at the side of the car is left open but after Sara sees Michael Myers at the window the door is shut. (00:30:15)
Continuity mistake: After Sara runs out of Michael Myers' bedroom window, he slices the bottom of her leg. But when she climbs up the roof there are no wounds. (01:07:00)
Continuity mistake: In the end, when Busta Rhymes is smashed into the wall, his dreads are really a mess. Next shot his dreads are neat. And the 3rd shot of Busta, his dreads are a mess again.
Plot hole: What exactly was Laurie Strode's plan in the teaser, when she strung Michael up over the edge of the roof. From the way she starts cutting the rope it looks like she plans to drop him, but she's seen him survive a 2-storey fall before, in the original Halloween, not to mention multiple stab wounds in H20. A fall off the roof into bushes would barely phase Michael.
Other mistake: This is a timing mistake. In the beginning of the movie, when Michael kills the first security guard, he stuffs his head in the washer. The second security guard was in the room within 30 seconds. There is no way that Michael had time to cut this guys head off, stuff it in the washing machine, turn it on, and hide before the second guard got there.
Plot hole: When Michael kills Rudy all of his knives are now gone but when he chases Sara around the house he has another knife with blood on it. Where did he get the other knife from? (01:04:30)
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 Sara is hiding in the garage she throws the chainsaw at Michael Myers and he manages to keep standing up but after Sara falls on the floor with the electrical circuits on top of her you see Michael Myers lying flat on the floor. (01:15:25)
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)
Revealing mistake: When Dr Mixter is talking about Carl Jung in the classroom the camera pans over the students and if you look at the blonde girl with the pink sweater on she stares at the camera for about a second. (00:16:35)
Factual error: Katee Sackhoff's name is misspelled "Katee Sachoff" in the opening credits.
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)
Answer: Or maybe he's thinking that his mission to kill Laurie is done. He's been trying to kill her for a long time and succeeded. No need to continue, but when those kids invaded his house, the killing began again. No one goes into his house, but him.