Other mistake: When Sidney is on the set with her mother's covered body, it rises up and reaches for her, speaking in her mom's voice. Sidney calls out for Dewey before climbing out of the window. However, when she's grabbed, she yells out her own name: Sidney.
Continuity mistake: Roman's sideburns change lengths towards the end of the movie.
Continuity mistake: At the end of the movie when Sidney is lying on the floor, Roman is pointing the gun to her head about to kill her. The gun is clearly pointing to her head/neck area when he shoots, but Sidney still lives and shows him she was wearing the vest. The vest protects her chest and Roman shot her in the head.
Revealing mistake: When the house blows up and Dewey, Gale and Jennifer jump off the balcony, we find that Gale is near the car, the killer jumps up behind her. Dewy takes a shot at him with a gun and it is obvious that the killer awkwardly slams himself against the car window, rather than being caused by the impact of the bullet.
Continuity mistake: Jennifer's house, the door just opened on its own. For some reason, Angelina and Tom don't shout back at Dewey and ask what's up, but rather jumpscare him. With Dewey's gun pointed at him, Tom has both hands in the air. In the same shot he lowers the right hand, but in the next he's with both hands up again. (00:43:20)
Continuity mistake: Look at the shirt David Arquette is wearing when he's out at lunch with Gale, heading then to Jennifer's house for the first time. They learn about Sarah's murder and head to the crime scene, and Arquette is wearing a different shirt he'll wear for the party later. Admitted by Wes Craven himself in the DVD commentary track. (00:33:40)
Continuity mistake: When fake-Gale mentions "your private self-loathing", an extra exits the frame to the left side. Over five seconds pass before the extra walks into another shot of the dialogue. And there she is again, but this time redoing her walk from the beginning, when Dewey embarrassed repeats "Little girl inside." (00:17:05)
Continuity mistake: When the cops go talk with Roman to ask him about his meeting with Sarah Darling, you can notice that Jennifer's bodyguard grew longer sideburns in the space of minutes since the scene at the house. Noticed by producer Marianne Maddalena on the DVD commentary track, and apparently they had some talks on set about that. (00:35:00)
Continuity mistake: After her dad visited her bringing her the essential dose of squashes, Sidney is sleeping on the couch. To get to her, the camera pans across a side table where there's a headset in front of a photo of Sid and her mom. Close-up on the photo, and the headset changed position as you can see from the colorful book it is resting on. (00:20:40 - 00:22:00)
Other mistake: Ghostface has a strength that rivals a superhero. He's trapped under a bookshelf but not only gets free in a second; the mere gesture of freeing himself sends a grown, bigger man flying and tumbling over a desk. Seriously, from the angle it appears that the case hit Cotton in the side of the head, but that would never propel him over furniture as shown. His body also twists counterclockwise when bumped and clockwise on the desk. (00:09:00)