Continuity mistake: Laurie's hair keeps changing throughout the movie. Her hair changes from wavy to straight while she babysits the kids. It is wavy again when she is going to Lindsey's house, and straight again when she is running back to Tommy's house. It stays straight until Michael starts to strangle her,where it becomes wavy again, having been straight in the previous shot. It all ends with straight hair. Surely all of this could not happen in a matter of hours.
Revealing mistake: In the scene where Dr. Sam Loomis is calling from a pay phone warning of Michael Myers return to Haddonfield, a Southern Pacific freight train passes by blowing its horn (you can't see the train in the standard version). While SP trains are quite common in Southern California where the film was made, they don't actually travel through any part of Illinois. (00:19:15)
Deliberate mistake: The opening camera scene, that's supposed to be shot from Michael's POV as a child, is too high as noted that he's almost face to face with his parents at the end of the scene and then is only mid-chest up to the father when he removes the mask. The POV is also too high as he walks across the dining room and as he approaches his sister upstairs.
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.amycamille1975