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.
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)
Continuity mistake: The word CORONER appears and disappears on the van.
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.