Revealing mistake: When Deckard and his friend are in his bedroom on the computer you see a window beside him and outside you can see that there are painted clouds on a wall. (00:20:20)
Continuity mistake: When you see Donna, Jim and Rudy approaching the house to get ready you see that they are the only ones on that side of the house. You can tell because the wall is on their left side, but in the next shot you also see Bill on the same side. Where did he come from? (00:30:35)
Continuity mistake: When Deckard is at the party he goes up to the opening doors and tries to sneak in. Inside you can just see a lamp and a few bronze pots on the floor but when he enters the room you can see lots and lots of furniture and objects in the room. (00:36:15)
Continuity mistake: When Michael Myers stabs the first two knives into Rudy and it goes through the door he gets the other one out of the drawer which is about three meters away but when he actually takes it out of the drawer and stabs it through him the drawer is like fifty centimeters away. (01:04:10)
Visible crew/equipment: Near the very end when Sara is walking through the tunnel in the house, the camera angle is in front of her. To the right, just for a split second, you can see someone's hand moving down very quickly. (01:12:50)
Continuity mistake: When there is a four-way split-screen while they enter the house, the top-left, the bottom-left, and the top-right don't match properly. (00:31:55)
Continuity mistake: At the start just after Willy sees his partner's head in the washing machine, he gets his throat cut and there is blood all over the knife. Later on when Michael is approaching Laurie's room, his knife just has blood on the tip, only halfway up the blade. (00:09:35 - 00:10:20)
Continuity mistake: When Sara gets locked in the closet after the mannequin falls on her, we see Rudy's fist bust through the closet door, as if there were no other way it. In the next shot, the closet doors are wide open.
Continuity mistake: Throughout this entire film, the interiors of the Myers' house are huge, compared to the small two story frame house exterior.
Continuity mistake: When Freddy rendezvous with the gang, Jen's hair when she is applauding at the back is tied in two scruffy bunches sticking out. A couple of seconds later, she has only one bunch tied. From then on, it is tied in two bunches. (00:21:30)
Continuity mistake: When Michael Myers is holding the tripod to impale the crewman, the length of the sharpened end changes in length and shape numerous times. First, it's wider and smaller. Then it's slightly longer and narrower. And when it's finally through the victim, it's long enough to go through the neck and into the adjacent wall.
Continuity mistake: When you see Deckard is in his room with his friend the second time Deckard is relaxed,leant back on his chair with his cheek resting on his fist but in the very next shot he is typing on his computer. (00:25:25)