When the prom queen is sitting on the bumper of the car in the wide-angle shot, her legs are in one position. The camera then cuts to a shot closer in, and her legs are in a different position.
Felicia is holding the handkerchief a few inches in front of her face, then the camera cuts to another angle, and she is holding it against her upper lip.
In the 89 prom scenes, many of the hairstyles look current and nothing like the 80s.