Audio problem: When Sam is talking to Ghostface for the first time, as Ghostface says the words "I'm going to show the world who you really are," the camera cuts to a different angle. If you watch Sam's chin at the top of the screen, you can blatantly tell that she's speaking, but no audio is heard.
Audio problem: When Sam leaves her apartment to go find Tara at the party, we hear her in the background unlock a single lock and open the door. However, earlier, we saw that there are four different locks on the door, and she relocked all of them. So we should have heard her unlock four locks before being able to leave.
Audio problem: When Sam returns to her apartment, we see that she's installed four separate locks on her door due to her fear. However, when she enters and relocks all the locks, you hear her re-locking six locks.
Audio problem: When Jason dies, he says the line, "But we have to finish the movie." If you pay attention, his mouth isn't moving for the word "but."
Answer: I think this is more "trivia" than mistake. There's no error in a film taking place a bit further ahead in time than in its release date.
TonyPH