Continuity mistake: In the scene where Gail and Dewey find the killer's voice changer, Gale's hands are clean, but when it shows her hands picking up the device, there's dried blood on them. But when it shows her hands again, the blood's gone. (01:16:05)
Continuity mistake: At the start of the movie when Cotton's girlfriend is being stalked by the killer, he stabs his knife through her bedroom door making a few large holes, especially with the first stab mark. Later, when Cotton finally gets to the house and is lookng for his girlfriend, he goes up to her door and there are now far smaller holes in the door, all in a nice pattern. When he smashes through the door, from the other side we can see there's no damage at all, then when his girlfriend emerges the stab marks are back, but in a different configuration. (00:07:35)
Continuity mistake: When Gale finds Roman in the coffin, there's no blood on Roman's elbow when the shot is closing in on the coffin. When Gale opens the coffin, the elbow is covered in blood. (01:17:40)
Continuity mistake: At the end of the movie, after Dewey asks Gale to marry him, she lays one on Dewey. She leans to the left of his face when they start kissing, and at a cut away long shot she suddenly is kissing on the right... then the close up is back at the left. (01:44:30)
Continuity mistake: When the actors, Gale and Dewey are hanging around in Jennifer's house, they realise a fax is coming through. When Jennifer first approaches the machine, notice that there is actually no paper in the machine. A few shots later, the paper supply has suddenly been replenished. (00:44:20)
Continuity mistake: Before Sidney pulls the killer out of the door on the house set, we see the bedside table is lengthwise against the wall. As the killer falls towards the bed it's turns 90 degrees, so the bed is a bit closer to the door. (01:05:45)
Continuity mistake: When Sarah tries to fix Roman's statue's head, her hair is over her face, when she goes to answer the phone her hair is pulled back behind her ear. (00:23:20)
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.