Early in the film, two references to concert sequences are dated July 1966. This is impossible, as Jan was injured April 12, 1966.
The first song they recorded was "Jenny Lee", and while Dean is in the Army Reserves the radio announcer announces the artist as Jan Berry, rather than Jan & Arnie.
The Corvette that Jan drives down the highway to his crash changes from a silver 1967 Corvette convertible with sidepipes to a silver blue 1964 convertible with no sidepipes as it crashes into the truck. The Corvette he actually crashed was a 1966 Corvette.
When Richard Hatch blows out the candles on his birthday cake and walks away from it, one of the candles stubbornly re-ignites itself and then continues to burn unnoticed by anyone.
At 33:00, there is a what appears to be a 1967 Corvette with a 1967 427 hood in the driveway. As Jan's accident was April 12, 1966, it would have been impossible for him to have a 1967 Corvette. The same Corvette is seen in the small Texas town and shows a passenger dash that is pre-1967 and a gas lid that is a 1965. Also, the hood doesn't have the factory stripe on the center bulge and scoop. This car appears to be made of parts that would not have been around in 1966 with the front end and hood.
At 46:35 after being at the Army office, Jan Berry is now driving down the road in a silver 1967 Corvette convertible. As this is the day he crashed, April 12, 1966, he has had two 1967 Corvettes in a very short time and five months before any were made.
In the scenes set from 1964 forward, Jan and Dean are shown wearing 'seventies-era feathered shag hairstyles. In reality, the duo donned brushed-back "dry" pompadours.
From 1964 onwards, Jan and Dean are shown wearing '70s-era feathered shag hairstyles. In reality, the duo donned brushed-back "dry" pompadours.