Continuity mistake: After another big reveal about her messed up family history, Sylvia goes to a pub and sits at the counter. Her arms are folded when seen from the front, or she's leaning with just her left when the camera is on the back. (01:05:35)
Factual error: "Venus" by Bananarama is playing when Brian gets home for Christmas. The song was released mid spring 1986, but the movie takes place in 1985.
Revealing mistake: Right after Sage plays chicken with the cops, the cop car is shown peeling out in reverse to follow her down the alley. The dust from the burnout is ejected towards the back of the car. Being a Crown Vic, the car has rear wheel drive but the dust should be moving opposite the car's direction. What this shows is that the car was actually being pulled backwards as it attempted to accelerate forwards. What's more is that even the sound is of a car spinning its tires opposite to being dragged. (00:12:50)