Factual error: In the scene when Laurie gets stabbed by Michael in the arm she falls over the banister - the camera shows a view of what she sees, falling at that angle Laurie would have broken her neck, spine and hip. But it is still weird how she managed to turn 180 degrees in such a short fall. (01:16:40)
Continuity mistake: In the beginning of the film when Michael is walking through the house, the clocks have different times on them. After he walks by the clock in the living room, it says 9:40. Seconds later, it strikes ten times.
Continuity mistake: When young Michael Myers sees the clown mask, Judith's clothing is bunched up together on the floor. When he puts the mask on, Judith's sweater is lying separately from the rest. (00:05:15)
Other mistake: Michael stabs the teen boy who goes to get a beer for his girlfriend. In the closeup, even though the teen boy was stabbed pretty much straight through the heart clear through to the wall, there is no blood whatsoever dripping on the floor or down his pants. If you cut the major arteries to the heart, there would be great volumes of blood streaming down both the front and back of the teen. Even if he missed the heart there should be blood.
Continuity mistake: When Laurie is in the closet she stabs Michael with the hanger and leaves it up there. When they show all the locations at the end of the movie, in the shot of the living room look near the floor up close - you can see part of the hanger there, even though it was left upstairs.
Continuity mistake: When Laurie, Annie and Lynda are walking home from school, the part where Lynda walks to her house you can see the station wagon on the side of the road behind them. A few seconds later it has moved up the side of the street.
Plot hole: Since the station wagon from the asylum was stolen, it should have been reported stolen along with the escape of Mike Myers. So why was the sheriff department not looking out for the stolen station wagon? We see Myers driving that station wagon freely without being stopped, while wearing a mask in broad daylight.
Continuity mistake: At the beginning of the film the Myers' house is within walking distance of the Strode house, both of which are on one side of town, while the Doyle and Wallace houses are on other considering the driving distance Annie and Laurie had to drive to get to them. But at the end of the film somehow the Myers' house is now within walking distance of the Doyle and Wallace houses.
Continuity mistake: At the beginning of the movie the only light on in the house is from Judith's room, which she turns off. Michael is seen walking through a dark house with only the hall light on. When he comes outside after killing Judith every window in the house has a light on. He didn't have time to turn them all on as he ran down the steps.