Other mistake: Watch the scene where the drunk Ben Tramer (wearing a similar Michael Myers mask) was hit by the speeding cop car and then pinned against the parked van before burning. Even taking out the equation of accidentally hitting Ben Tramer, what was the cop car doing speeding at that rate of speed, head on towards a parked van on a side street? Remember, we only hear screeching brakes AFTER the car hits Tramer, and we never see the cop car swerve or any of that to miss hitting the van. Seems that even if Tramer hadn't been there, the cop car was sure to barge head on right into that van.
Other mistake: When Joan is cutting up her rose garden, she is ranting and raving about how mad she is at Mayer, and how they're calling her box office poison. But if you look closely at her lips, they aren't moving.
Other mistake: For corpses which have spent around a decade lying in water, the zombies' hair and uniforms are surprisingly well-groomed.
Other mistake: When David changes into a werewolf for the first time you can see his huge feet vibrate when he moves his legs in agony: they are made from rubber.