When Evel Knievel crashes the Stratocycle through the front door of the mental hospital, the cycle's right wing breaks against the door frame, but the left wing remains intact. As Knievel rides down the hall in the next shot, both the right and left wings are missing. In a shot after a quick pan-away (showing the Doctor calling security), Knievel reaches the end of the hallway, and both wings on the bike are intact again.
When Jessie takes over as Evel in Mexico, he leaves the shack at the top of the ramp not wearing gloves. But, in the slow-motion footage of him crashing, he is wearing gloves. Also, in the slo-mo, he is shown tumbling on dirt, but in the next shot back at regular speed, there is green grass all around him.
During this film various characters put on helmets 20+ times and never does anyone use a chin strap, thus rendering the helmets basically useless.
In the Mexican jump the device the mechanic installed is supposed to cause the front tire to blow out, but in the footage of the crash the front tire is still intact. Plus, the explosion on the front tire is obviously an animation done in post.
When Evel gives Kate a ride on his motorcycle in the parking lot of the stadium in Long Beach, he does a "wheelie". In the quick close-up shot of the pair, they are going much slower than is possible - note how slow the parking lines are moving - or in comparison to the longer shots of them.
Evel is shown picking a lock to Will's padded cell with only one tool - the pick or rake. He does not use the second tool needed to actually turn the lock.