Continuity mistake: In the yearbook photo of Laurie it says class of 78. She just started her senior year a few months earlier, so she would be class of 79.
Character mistake: In the beginning where they are showing all the newspaper articles, the article uses Michael "Meyers" twice in one article and then back to "Myers."
Continuity mistake: Although I understand the fact that H20 didn't want to include the Halloween 4, 5 and 6 timeline, Michael was burnt to a crisp by Dr. Loomis in the epilogue of Halloween 2, so he should have a fully burnt body. Also Michael was shot twice by Laurie in Halloween 2... He would have at least had scars/damage to his face in H20.
Suggested correction: This is addressed and left unexplained in the film, as Laurie's son doesn't believe Myers could have possibly survived the events of 'Halloween II' but apparently has anyway. We are left to speculate whether 'Halloween II' had truly ended the way we had seen, or if the recent killings were not actually by Myers but a copycat stalker, or if Myers is supernatural, etc. Viewers are free to consider this a bad or stupid choice if they wish, but strictly speaking it isn't a mistake.
Continuity mistake: Jimmy opens the fridge. On the second shelf there are no packages of lunch meat. A few seconds later a pack appears, and shortly after that 4 more appear out of nowhere. (00:04:10)
Plot hole: At the end of the film all the police and ambulance vehicles manage to get into the school, but earlier Keri/Laurie smashed the mechanism that opens the gate.
Continuity mistake: The word CORONER appears and disappears on the van.
Character mistake: The newspaper article seen during the opening credits dates the Halloween murders (the events of the first and second film) as taking place in 1968, when they in fact took place in 1978.
Continuity mistake: When Sarah is in the dumb waiter with Charlie, she looks down at the cut on her leg, then at him, and he's looking straight forward and up. In the next shot, as the dumb waiter reaches the top, his head is turned, looking at her, and remains that way until she exits and the dumb waiter drops when Michael cuts the rope.
