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)
Continuity mistake: When Gale stumbles into Dewey for the first time, the camera is behind her and as he mutters "Gale" you can see her shoulder, which is clear from any hair. Next view, and her shoulder is a big messy wig salad. (00:16:40)
Continuity mistake: Gale Weathers just finished her speech, and David Arquette's brother in the audience asks her a question. Of course, they are out of time, and he's silenced with applause. People start leaving their seats, but the people standing don't match in the reverse shot. (00:11:55)
Continuity mistake: For a moment, Cotton seems to have the upper hand against Ghostface as he pushes a bookcase on him. He eyes the golf club trying to take it back; in two consecutive shots though, you can see a Vance Bourjaily book (it should be "Now Playing at Canterbury" but you can only see the back cover) that faces opposite directions. (00:09:00)
Continuity mistake: The detective gives Gale the picture that she identifies; her thumb is in a different spot in each shot. (00:12:30)
Continuity mistake: Detective Kinkaid tells Gale "I'm here because Cotton Weary's been murdered." Behind him in the corridor, a girl that was at the conference, in overals and a loud pink top. Reaction shot on Gale, and in the background, in a different corridor, the familiar denim-and-pink-girl. (00:12:20)
Continuity mistake: Cotton agonizes on the floor with his right arm raised, but for the views with the camera pointed at the killer, his arm is lowered. (00:09:10)
Continuity mistake: Cotton arrives at his apartment; seen from behind, he leans into the door putting his right hand on the frame. Side view and he's leading with the left. Very similar mistake a handful of seconds later; look when he moves up the stairs. He gets one foot on the last step and it's the right foot, then it happens again, but it's the left foot that leads. (00:06:20)
Continuity mistake: Christine turns off the stereo. Look at her hair, and keep looking as she walks along the corridor. The hair keeps changing position over her shoulders between takes. (00:04:50)
Continuity mistake: Cotton is talking in traffic using his car phone. Notice the way he holds it in the very first shot; his pinky finger is behind the receiver, but it's on a different position after the cut. (00:00:35)
Continuity mistake: In the scene where Dewey and Gale are having lunch, Dewey asks her "Why would the police come to you?" In the background, a waitress in white walks by. Then they switch to Gale and the waitress has vanished. (00:28:30)
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.
Answer: Not expressly, though it could have been the date of some significant event (December of 1988) but someone as security-conscious as Sydney now is wouldn't be stupid enough to have her code be something that could be guessed.