Continuity mistake: In the last scene of the movie Tommy is sitting in the boat on the lake with no wind. As he talks to his dad there is no rope above his shoulder in the pulley at the end of the boom. After the wind picks up and he gets hit in the head with the boom there is a rope on the pulley. (01:32:30)
Continuity mistake: When Richard and Tommy are trying to sell brake pads and Tommy eventually catches the model car on fire, Tommy eventually sets a blue model car on a pad of paper where a couple of things happen. First, when Tommy says "I CAN'T STOP!" the right front tire on the blue model is all of a sudden bent outward. After Tommy destroys and catches the other model on fire, not only does the tire fix itself, but the car changes positions on the pad of paper numerous times.
Continuity mistake: Three types of airplanes are used for the flight to Chicago. The exterior loading and taxi shots show a Boeing 747. The interior shots show another Boeing (the overhead bins, sidewall panels, etc., are distinctively Boeing), but it's smaller like a 767, because it only has 2 seats by the window and 3 in the center. The exterior shot in flight shows a Lockheed L1011, with its distinctive S-duct for the center engine.
Factual error: When Paul flies off the hood of the crash test car when it stops, he should have kept going in a straight line. Instead, he flies off to the side at a sharp angle and lands in the seat testing department.
Deliberate mistake: Why would Richard, big Tom's 'right hand man,' have to drive his cherished vintage car on a business trip that would take him hundreds, if not a thousand miles? He surely could have taken a company vehicle. Of course, then they couldn't do the 'car slowly and humorously being destroyed' shtick.