Factual error: There are a few scenes in the movie which show Christine locking her doors and we see that she has common lock "buttons" on the inside door panels. This is incorrect - 1958 Plymouths are not equipped with buttons. To lock the door, the door handle has to be rotated counter-clockwise.
Factual error: When Arnie goes to visit Dennis in the hospital, on Thanksgiving, the date November 23 is shown just before the camera pans across the TV which is on and it shows the Oakland Raiders playing the Detroit Lions. That year the Lions played the Broncos on Thanksgiving. Three days later, on Sunday, the Raiders played the Seattle Seahawks. That Season though the Lions did play the Raiders on November 19, which would have been 4 days before.