Continuity mistake: When Jim and Mike are in the car discussing his split form the Stray Cats, the camera is looking through the rear window showing that they are about to be overtaken by a blue car. But when the camera angles changes to the side window, they are overtaken by a red truck and the blue car has disappeared.
Factual error: During the launderette scene, cars from the 1970's can be seen through the window driving along the road outside.
Factual error: Shortly after buying the van, the group call at a guest house and the Zombies song "She's Not There" is playing on the radio. This was not issued until 1964. This scene is set around the time of president Kennedy's assassination in 1963.
Revealing mistake: In most scenes where you see the group's van, it has the year letter on the number plate covered up. But when they park outside their manager's office, you can see that it has an F registration dating from 1967/8, meaning it would be too modern for the early part of the film.
Factual error: While the Stray Cats are in the hotel during their 1966 tour of the USA, the Bee Gees song "I Gotta Get a Message to You" is played. This was not issued until 1968.
Other mistake: When counting out Adam Faith in the boxing match, the referee counts 1 - 4 in Spanish then (with his back turned to camera) adds 'cinque' - Italian. I suspect this was dubbed post-production because the location of the scene was in Spain and the actor Spanish.