Continuity mistake: When Billy jumps on Sidney in the corridor making his comeback, a bag of potato chips that was lying against the bench's armrest goes from vertical to horizontal. It wouldn't be surprising that a small and possibly mostly empty bag would be toppled over considering the movement that just occurred, however when Sidney headshots Zombie Billy the bag is back being vertical. (01:41:20 - 01:42:30)
Continuity mistake: In the final scene where Sidney gives the "coup de grace" to Billy shooting him in the head after he suddenly woke up, he holds the left arm above the mask on his top left, but when he dies, his arm is lowered and the knife appears from nowhere. (01:42:30)
Continuity mistake: Pay attention to the scene where Randy gets the call that the principal is dead and the rest of the group races off to try to see the body before they cut it down. Five or so people get up and run towards the door. When they are shown in the exterior shot running from the house to the car it is an entirely different group that are not even dressed similarly. This was due to the fact that the group were made up of actors whose contracts were by the week. The exterior shot was the only thing they didn't get during that initial week and to bring them back for that one shot they would have had to have been paid for an entire new week, which was too expensive for one shot. They just used extras instead.
Continuity mistake: At the very end, when Sid finds out who the killers are, they are all standing in the kitchen. When Billy and Stu stab each other take a look at the blood stain on the left side of Stu's jumper. It starts around his shoulder and vertically goes down towards his waist. When Sid is fighting him in the lounge she gets up and goes behind the TV. In the shot looking straight down on Stu from a birds eye view, notice the blood stain is now horizontally across his stomach. You'll have to look closely for this one.
Continuity mistake: The Halloween scenes in the movie don't match up. For example, Randy is watching the part where JLC first discovers the bodies. About ten movie minutes later in Halloween, she's hiding from Michael Myers in the closet. Then Billy gets the idea to search for Sidney, because that's the scene currently playing. Too much time occurs between scenes for this to occur.
Continuity mistake: When Skeet is first shot by Gale he crawls backward, but if you look at the ghost face behind him there is no knife there. The next shot there is a knife on top of the ghost face.
Continuity mistake: After the killer calls Casey the second time she puts a salt shaker on the counter, she walks round to her living room, and the killer phones her two more times. When she gets back to the kitchen the salt shaker has disappeared.
Continuity mistake: Sidney is rather inexplicably covered in blood when she reappears to stop Gale from driving off in the news van without her (even her hair is drenched!). It's true she'd been off-screen for a while and who knows what's happened to her, but it's hard to come up with an explanation from what we've seen, especially since the implication is that she's simply been hiding out in the fields this whole time.
Continuity mistake: When the whole gang is watching Halloween, they see the scene in which Michael Myers impales a victim with a knife, which suspends him from the wall. Just before Randy pauses the movie, Michael Myers is standing and admiring his handiwork. When Randy pauses it, the frame is of Michael Myers raising the knife, which of course, happened 10-15 seconds ago.
Continuity mistake: When Stu puts the voice box and phone in Sidney's dad's jacket pocket and lets him fall, when he hits the ground the voice box partly falls out, but then when they show the dad again the voice box is tucked back in.
Continuity mistake: At the beginning of the movie as Ghostface chases Drew Barrymore the killer is wearing a different style of mask and even has a shiny silver material rather than black. As the killer then sits on top of her then choking her, it is the more recognisable mask.
Continuity mistake: At the end when Sidney is in Dewey's police car and the killer is there, she opens the door and falls out but the door is still locked. In some cars you can open the door when it is locked but the lock always pops up after you open the door, and this one didn't.
Continuity mistake: When Randy answers the phone he kneels down putting his head about level with the top of the TV, yet when Sidney goes to drop the TV on Stu's head the TV is much higher.
Continuity mistake: Sidney is on the roof trying to escape from the killer and she falls off. When she gets up she sees the dead body of Tatum in the cat door and her left arm must be behind her because you can't see it but this isn't what happened when you saw her die. Her left arm was inside the garage and was beside her. Unless if fell off, it should be next to her body.
Continuity mistake: When the cameraman is watching the 30 second delay footage and the ghost face is about to kill Randy who is on the sofa, he walks into the room in a different way on the delayed footage to on the actual film footage.
