Other mistake: In the scene where Jamie is in the closet, looking at a photo of her mother (Jamie Lee Curtis). The photo looks exactly like the scene where Laurie is sitting waiting for Annie on the ledge in the original Halloween, which wasn't photographed at the time, it's clearly a still from the movie.
Other mistake: As the brown truck drives away in the scene after the man working in the newspaper office is "harpooned" by a Critter, if you look closely as the truck turns a corner you can see some Critters rolling after it. Well, after they roll past the truck in the bottom left of the screen you can see the Critters roll right smack into another parked car. Obviously the crew forgot to add a turning feature to their Critter balls (which were just some fur taped to a basket ball).
Other mistake: The Giant Killer Klown at the end of the movie picks up the Ice Cream truck and hurls it into the wall resulting in an explosion that destroys the entire car. The two ice cream drivers say that the way they lived was by hiding in the ice cream truck freezer. First, ice cream truck freezers cannot fit two people and even if they could, the car was blown apart from the back first which would have killed them instantly anyway.
Other mistake: When Jack stumbles into the wrong bedroom, he witnesses Mary's murder twice. Later, Mary reveals that she gets murdered only once every night.