Deliberate mistake: In the final shot of the film, Jill's head moves slightly when she's supposed to be dead. In the commentary, Wes Craven confirmed this wasn't strictly intentional, but he decided to leave the take in on purpose in case he decided to bring her back in a future installment. But unless a sequel proves she's still alive, it's technically a mistake, albeit a deliberate one.
Scream 4 (2011)
1 deliberate mistake
Directed by: Wes Craven
Starring: Courteney Cox, David Arquette, Neve Campbell, Lucy Hale
Continuity mistake: When Sidney is in Olivia's room right after she killed, Sidney is holding onto the very bloody door frame, getting a little on her hands. The next shot when she picks up the phone, seconds later, there is no blood to be seen on her. (00:36:30)
Sidney Prescott: Don't fuck with the original!
Trivia: Towards the beginning of the movie when Emma Roberts and Hayden Panettiere are standing in the hallway next to their lockers at school, next to them is a bust of Henry Winkler's character who played the principal in the first film and was killed.
Question: When Jill and Kirby were watching "Shaun of the Dead", and Ghostface calls them, how did he know they were watching that?
Answer: Also, pretty sure they told Olivia over the phone what they were watching and Ghostface was in the closet listening.
Answer: Remember that Jill and Charlie were the killers and were working together. Therefore, Jill probably told Charlie the film they were planning on watching. Meaning when he called Kirby he knew what she and Jill were watching, which makes the killer more sinister and omnipresent.