Continuity mistake: At the party, Randy asks (with a weird "yeeeeh!" that appears to be dubbed over) how many "hellraisers" are there. Matthew Lillard points at Rose McGowan two times in two different shots and not with the same hand either. (01:02:55)
Continuity mistake: Kenny passes the camera to Gale as she fetches the coat. The hand he used to slip her the camera joins the other hand on top of a plastic case, but in the next shot his right arm is again lowered. (01:02:45)
Continuity mistake: When Randy shouts overenthusiastically that there's a simple formula to the murders, the extras in the background change position in the next shot when there's a whole shot dedicated to their reaction. (00:56:45)
Continuity mistake: In the close-up when she tells Sid not to 'freak yourself out' because they have a long night ahead, the light on Tatum is wildly different from the rest of the scene. (00:54:30)
Continuity mistake: During the whole bathroom scene the trash bin by the exit door is oriented parallel to the wall or perpendicular. The mistake can already be spotted early in the scene when the cheerleader is berating Sidney, but it is much easier to notice it at the very end not just because there are multiple consecutive shots from different angles, but also because to make possible for Sid to collide with the bin as she slides across the floor, the bin has been placed almost two feet away from the wall. (00:46:30)
Continuity mistake: When some goof runs around the corridors of the school screaming, Neve Campbell's hair changes position over her shoulders between shots. (00:42:25)
Continuity mistake: Gale realised that Cotton is innocent, and she talks about it to the cameraman. In that part of the scene, the sun is on Kenny at a different angle in different camera angles (look at the reflection of the rays in his hair and jacket). (00:41:55)
Continuity mistake: When Sidney walks towards Gale's van to talk to her the day after she socked her, she passes by the same two students in two shots. (00:40:00)
Continuity mistake: Sidney's right hand is in a different position in the two shots that happen when Tatum's mother tells her that there's someone at the phone for her. (00:37:30)
Continuity mistake: Inside Tatum's bedroom, Dewey tosses Sidney an ice pack for her sore hand. Look at Rose McGowan's left hand; she's holding the plush bunny in a different spot between shots. (00:37:00)
Continuity mistake: When Sidney punches Gale in the face, she flies back against her cameraman that catches her putting his hand on her side under the armpit. In the next shot Kenny's hand is on the upper arm, and Gale is also already holding her cheek. (00:36:35)
Continuity mistake: When Gale Weathers 'interviews' Sidney in the back alley, the microphone is turned at different angles between shots. (00:36:30)
Continuity mistake: Tatum is growing impatient while Sidney is sitting in the police station waiting to be released, and she hurries her brother. In this sequence there is a blatant lack of continuity whenever the editing switches to reverse shots, as Rose McGowan's hand and Neve Campbell's movements don't match between angles. (00:35:25)
Visible crew/equipment: When the officers take Billy away from Sidney's house, a set of lights is reflected in the back window of the car. (00:31:00)
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: In the scene where Tatum gets closed in the garage door, the first time it shows her arm hanging down. In the next scene, it shows her arm caught in the door. (01:07:30 - 01:22:15)
Continuity mistake: When the killer sneaks up on Randy, Randy is lying back against the sofa. When Ghostface raises the knife Randy is lying back, relaxed with a tired look on his face. On the delayed footage when the killer raises the knife, Randy leans forward and is practically on the edge of the seat, his mouth and eyes wide open. (01:22:55 - 01:23:30)
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: The first time that Casey Becker is stabbed by the ghostface, you can see the knife go into her chest, very deeply, but no blood is there, but directly in the next shot, her shirt is covered in blood. (00:10:50)
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.
Answer: This is according to IMDb: When Sidney comes out of the closet and stabs Billy with an umbrella, the stunt man was supposed to hit a pad on Skeet Ulrich's chest. The first hit got the pad but the second one slipped and hit him in the chest (you can see it in his reaction). Wes Craven kept it in because of its authenticity.
Shannon Jackson