Continuity mistake: Dr. Loomis seems to make the trip from Haddonfield to Smith's Grove (150 miles apart) in an impossibly short time.
Continuity mistake: When Tommy goes back to the bus depot, he finds a blood trail that was left by Jamie when she died the previous night. Tommy's there during the day or early morning and when Tommy finds the blood in the sink, he touches it and it's still wet. Blood dries in only 4 minutes so it couldn't have been left by Jamie.
Continuity mistake: Tommy goes to the bus station and a map of the towns of Illinois appears on the wall. Notice that Haddonfield and Smiths Grove (150 miles apart in the film) are located in between Pontiac and Dwight which are 18 miles apart in reality! That's how far apart the Amtrak stations are from each other according to the Amtrak timetable/schedule.
Plot hole: Michael kills Mrs Strode outside, in the backyard, splattering blood everywhere. 6 seconds later, Kara comes home from school. Michael cleans up the blood, puts the sheets in the washer, and puts Mrs Strode in the attic in the one minute 5 seconds that it takes Kara to walk to the back yard and look around.
Continuity mistake: In the opening of the original Halloween, the backyard of the Myers house is level with the back door leading to the kitchen. In this movie, the kitchen door is accessed by steps showing that it is high off the ground, and also means that the house is on an embankment. If this is true, why does Kara walk on completely flat ground while going by the side of the house?
Continuity mistake: In the scene where Michael Myers impales the nurse's head on a spike in the darkened hallway, we first see Michael walking mysteriously out of the darkness & in plain sight of the nurse. Then the camera angle changes to Michael's POV and he doesn't see the nurse until he walks around the corner.
Visible crew/equipment: When Jamie is driving the pickup truck and Michael Myers is driving the van chasing her right when Michael turns the headlights on you can see two people in the van.
Continuity mistake: As the film progresses towards the third and final act, Michael's body goes from large and muscular to lean and thinner. No attempt is made to hide this. The reason is because the director decided to change the ending but didn't bring in the original actor, instead choosing a second one whose body doesn't match.
Factual error: In the Scene where they just finished having sex, Kara calls and tell them that Michael is in the house. But when Kara calls, the girl picks up, but she picks up a cordless phone. But there's no power, the hand set will work on the battery but the base needs to be plugged into a power source to make and receive calls.
Plot hole: Why does Michael decide to kill Barry in the first place? Was he listening to the radio and offended by the comments that he made at the beginning of the film? (Though there is an explanation on the DVD's 'Producer's Cut', it remains a mistake.)
Continuity mistake: At the bus station, Tommy finds a trail of blood left by Jamie, and also finds blood in the sink. Don't you think it would have been cleaned up by the time Tommy got there?
Continuity mistake: The blood on Jamie's chin changes from shot-to-shot when she is being impaled on the farm equipment.