Continuity mistake: The Myers house was a small Victorian house in all the other films, but in this one it's a huge gothic mansion.
Revealing mistake: When Spitz is stabbed with the pitchfork, you can see the line where the fake chest is. It's a different color.
Revealing mistake: In the beginning when Michael crawls out of the mine shaft that was just bombed he floats downstream. You see that he floats up to the old man's dock. If you look at him you can clearly see that he is wearing a black lifejacket. The filmmakers didn't even try to hide it under his suit, it is clearly visible on the outside of his jumpsuit.
Visible crew/equipment: When the punk Mikey was waxing his car, you can see a stage light in the reflection of the car.
Audio problem: When Tina is in the car with who she thinks is her boyfriend but is really Michael Myers; watch her lips when she says the line "Nothing Mike, that's what I get, Nothing." It is obvious that this line was dubbed in over something else as her lips do not match that particular line. (00:42:55)
Continuity mistake: When Michael Myers is chasing Billy at the farm in the car, his position changes as he is driving - he is on the passenger side several times then on the driver side.
Audio problem: Watch closely to the scene right after Tina is stabbed and Billy is trying to pull Jaime away from her. There is a part where in the dimly lit bushes where Jaime keeps yelling "Tina", but her lips aren't moving.
Audio problem: When Sam is fighting Michael in the barn she says "you son of a bitch", but her mouth is closed.
Revealing mistake: When Michael (dressed up as Mikey) brakes the car when Tina asks him to stop at the store, you see that when he brakes, the rear red lights don't come on. (01:13:25)
Continuity mistake: In the scene were Tina asks Michael to stop the car at the store he starts driving faster going at least 30mph for 7 seconds. When he finally stops and backs up he drives about 5-10mph and ends up outside the store in 4 seconds.
Visible crew/equipment: While Mikey is shinning his car (as well as the stage light already listed as a mistake), as he goes along the side panel, just before the side mirror goes out of shot you can see the camera go past and a guys head in the reflection of the mirror.
Other mistake: In addition to the brake lights, there are no lights at all on the back of the car when you see it driven from behind. However, you can see that the lights are on from the front of the car.