Revealing mistake: Magnum neutralizes the pursuer at the gas station jacking his car. In the close-up of the wheels spinning with no traction and then stopping, the hubcap is in pristine condition, but in the next one, it sports a dent already from a previous take. (00:15:20)
Revealing mistake: When the guy tricked by Magnum gets out of the car, check out of the very right side of the frame. You can actually see the hand of one crew member releasing the garage jack's lock, so that, when the car is kicked, the relatively light impact is enough to release the hydraulic lift and make the car comically bounce back on the ground. (00:15:25)
Revealing mistake: During the jogging phase, which may not be hazardous but surely is defatigating, Tom Selleck is replaced consistently and noticeably (except the close-ups, of course) by his stunt double Tom Lupo. (00:40:35)