Continuity mistake: When mom finds the failed test in Les's pocket, it is folded into eighths. Later, when dad shows the failed test to Les, it has only been folded into thirds.
Continuity mistake: When Les pushes the Cadillac out of the driveway, you can see the Audi in the corner of the screen, but earlier, his sister had already taken it for the night.
Continuity mistake: When Les' DMV examiner talks about his coffee being hot and filled "right to the brim" the amount in the cup increases between shots.
Continuity mistake: In most of the film, the Cadillac has personalized license plates reading "GRANPA" or "GRANDPA", except at the drive-in restaurant, where the license plates read "BDR 529" (also the number on the Bluesmobile in "The Blues Brothers"). When they drive away from the restaurant, the "GRANPA" plate seems to shimmer and move around - an apparent traveling matte made in an attempt to correct the error.
Continuity mistake: During the opening scene where Les is driving the Ferrari, the front license plate appears, then disappears, appears then disappears.
Continuity mistake: When the drunk driver is asleep in the Cadillac while he's going down the road, two of the four headlights are out. But later, right before the car is about to go off the hill, all four lights are working.
Continuity mistake: When Les' dad pours the champagne, the glass is full of foam, but when the camera angle changes, the foam has suddenly completely disappeared between shots.
Continuity mistake: When Les pushes the Cadillac out of the garage, he leaves the driver's door open as he goes to turn off the garage light. When the car continues to roll across the lawn and through a hedge, the door is closed and he cannot open it in time to stop the car.
Continuity mistake: You can see the stuntman driving when then guy is flung from the hood leaving Archie's. (01:02:05)
Continuity mistake: When Dean is flashing the camera in the back seat, you can see the stunt man driving when the car does the 360s. (00:55:35)
