Audio problem: When Sidney comes running to the house and she sees Dewey come out with the knife in his back she screams "Dewey!" but her mouth says "no!" (01:27:23)
Audio problem: When Gale is talking to Kenny the cameraman before she goes off to investigate the abandoned car with Dewey her face is in a close up. She can be clearly heard uttering the forbidden phrase "I'll be right back." However her mouth can clearly be seen saying "keep watching." (01:11:25)
Continuity mistake: When Ghostface is trying to kill Tatum in the garage, she tries to go through the doggie door. From the outside shot, she is out of the door from her arms and up. From the inside shot, she is out of the door from her hips and up. (01:04:20)
Revealing mistake: After Gale backs the van up, and Kenny's body falls on the windshield, they cut to a shot where Gale is driving away, and Kenny's body is on the roof of the van. When she starts driving you can clearly see Kenny lift his head into the air to look forward, even though he's dead.
Revealing mistake: When the killer surprises Sid after she's come in from outside and locked the door, he tries to stab her with his left hand, misses, and hits the door right next to the chain in closeup. In wide shot (very quick shot) when Sid legs it, look at the killer and you can see he's holding a very badly bent knife in his right hand, nowhere near the chain. (00:27:55)
Continuity mistake: As Gale is talking to Dewey outside the school, when she is trying to get information from him about the killings, Dewey takes his sunglasses off and hangs them on his shirt. In the following scene they hang two different ways every time the camera cuts to him. (00:48:40)
Continuity mistake: After the curfew has taken effect, Dewey and Sheriff Burke are standing on a sidewalk in town. The Sheriff is smoking a cigarette. In one shot the cigarette is almost gone, then he drops it and he steps on it, but it's now a lot longer. (00:59:40)
Revealing mistake: When Sidney and Stu are fighting in the living room and they both trip over the couch, Stu's stunt double is visible and wearing a wig. (01:40:25)
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: When Tatum is throwing beer bottles at ghost face in the garage, there is beer and foam all over his costume...until he lands on the stairs behind her. (01:04:10)
Continuity mistake: When Stu & Billy are in the kitchen after Sydney has escaped them, she calls Stu's house phone. Billy gets pissed and throws the receiver at Stu. It bounces off him and lands on the floor, yet when Stu picks up the receiver to talk to Sydney, it's on the table. (01:39:05)
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.
Audio problem: When Gale starts driving away after she hits Randy with the phone, Kenny's body falls on her windshield. At this part the camera pans to a shot overhead and Gale says "Kenny, I'm sorry, but get off my f***ing windshield!". Her mouth is not moving as she says this. (01:26:35)