Continuity mistake: When Kyle tells Jack that once he can get the remote, he will then be able to choose the channel. The position of the remote changes 90 degrees instantly. (00:18:30)
Continuity mistake: In the diner scene JB drops his pen when KG goes over to the girls. Camera changes and JB has got his pen in his hand again. (00:44:30)
Continuity mistake: When JB and KG are powersliding under the gate in the Rock n' Roll history museum, in one of the shots the gate is so far down that they would not be able to slide under. In the next shot the gate has moved up. (01:07:00 - 01:12:00)
Continuity mistake: Just after KG and JB swerve round the lorry, the lorry disappears from the road. It should be visible as it doesn't drive off the road. (01:12:10)
Continuity mistake: The scratch marks left by Satan at the end change length instantly. (01:22:20)
Continuity mistake: When JB dreams about singing "Master Exploder" in the small bar, he points at one guy in the audience and literally blows his mind. When he starts pointing you can not only see JB's face, but also how his elbow is in a slight angle. In the next shot the camera shows the guy JB is pointing at and his elbow is completely stretched. The views change several times and the angle of his elbow changes after every cut, until the guy's brain is finally blown out.
Continuity mistake: As Jack and Kyle are walking up the "Guitarway to Heaven" in the Rock Museum, they vary between marching completely in synch with each other and out of synch. They are still walking directly next to each other, so it is not due to one of them changing their pace.
Continuity mistake: When JB is in Hollywood for the first time and the guy plays Bach, you can see two Goths walk past and in the next shot the same guys walk past again.
Continuity mistake: During the car chase scene you can notice multiple stickers on the doors of Lee's car, but as soon as they show Lee watching the news, the stickers disappear in the subsequent shots of the chase.