Goofs

In the final race, although Watts and his father switch engines, the original engine is still seen at the back of the kart.

Vic claims that he knew he wanted to build engines on 14 February 1976 while watching the Daytona 500. The Daytona 500 in 1976 was held on February 15th, not February 14th.

Go Karts use 2 cycle engines that make a whine like a chainsaw. They also use a single speed centrifugal clutch that engage or disengage as the engine speeds up or slows down. During the racing scenes the sound effects are of cars shifting and downshifting and the engines sound like a Ferrari.

Set in the US but on Vic and Watts return from the police station, on the speed limit sign, it's clearly written MAXIMUM 70. It's in Km/h not in MPH. That would be faster then the 60 MPH speed limit on US highways. Not bad for a small country road.