Other mistake: After Michael kills Laurie at the beginning, he hands the knife to the inmate with the clown mask. The next kill is the cameraman for which he uses the tripod ends. A few scenes later they show Michael standing holding a knife with fresh blood on it. He hasn't killed anybody with this knife yet so where did the blood come from?
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.
Other mistake: When Freddy and Sara walk down the stairs after hanging Michael Myers with the camera cord, neither of them notices Jen's head lying on the floor. You'd think that they'd react in some way to this. (01:11:15)
Other mistake: When Donna is in the basement by herself, she sees a picture of Laurie cut out of a newspaper. This is a picture of her from Halloween (1978) when she was waiting for Annie to pick her up. So where did it come from?
Answer: At first impression, Laurie was catatonic not only from the shock of killing an innocent man, but also from a lifetime of being chased down by her murderous brother. She obviously knows from past experiences that nothing she does (including faking her own death) will stop Michael from finding her. It is later revealed she has been faking her mental issues (think when she has been hiding her regular meds in the raggedy Ann doll) and is committed only to stopping Michael, no matter what the cost. She may have also been trying to protect her son and the only way to do that is to allow herself to be institutionalized in order to lure Michael there.