Continuity mistake: Dabney Coleman and the villain fight on the scaffolding on the side of a skyscraper high above the city. They are the only two people on the scaffold, but during the fight at the bottom of the screen you can clearly see a man's head.
Continuity mistake: During the car chase, the bad guys are in front, followed by several marked police cars, then by the red unmarked car; they are all on a curved exit ramp (after the construction zone). In wide shots with no bullets hitting them, the marked cars are Dodge Diplomats, same as the unmarked red car. But in close-ups, when bullets are striking them, the marked cars magically become Chevrolet Caprices. This occurs at least twice. (VHS version.)
Continuity mistake: During the chase scene when the two cars are side by side down an alley, one car is scraping the guard rail and making sparks, but in the background the guard rail is still sparking with no car near it.
Revealing mistake: Throughout the car chase, the same white Plymouth Volare coupe is seen over and over, sometimes parked, sometimes being passed going in the same direction, coming head-on, or getting bumped out of the way.
Visible crew/equipment: During the final battle between Simpson and Stark outside a skyscraper, after the scaffold breaks, there is a dark platform visible at the bottom of the screen as the camera moves down to reveal the ground, quite possibly the floor of a helicopter. (01:25:00)
Other mistake: If Burt honestly believes he only has days left to live, wouldn't he be wondering why he isn't displaying any symptoms of illness (coughing, fever, pain etc). Also why wasn't he prescribed any kind of medication by the doctor who gave him this prognosis. Kinda silly really.