Revealing: When Les' mom is doing the laundry and "finds" the Test Failed notice, you can see that she actually had it in her hands the entire time. She transfers it from one hand into the other, then puts the hand with the paper into the pocket and pulls it right back out, then knocks it off onto the floor, and acts surprised.

Continuity: 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: 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: 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: 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.

Visible crew/equipment: In the beginning, when Les, his dad, and Dean are discussing cleaning the garage, stage lights are reflected in Dean's sunglasses.

Continuity: When Les' DMV examiner talks about his coffee being hot and filled "right to the brim" the amount in the cup increases between shots.

Visible crew/equipment: When Feldman is giving Haim a ride home on his bike, you can briefly see it is a large tricycle he is riding. Large rear wheels can briefly be seen when they are riding through the trees.

Factual error: There is no way the DMV will pass one twin based on the fact that his twin passed, even though they ended up taking his license. The mistake was giving it to him in the first place based on the fact his twin passed.

Continuity: 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: 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.

Factual error: Les' friends and sister are shown getting their real licenses (the actual cards, with photo) right away, the same day as their test. But in California, where they live, you don't get your license for six weeks or so - until then, you get a paper printout.