Revealing mistake: When Jim hits the brakes in his stolen patrol car, the two pursuing police cars turn and flip over and over. As they roll, the 'roll cannon' is visible on the underside of one of the cars (a round steel tube in a hole in the floor) and at left, the two cannon slugs from both cars bounce down the road. This device fires the slug downward, and the force behind it lifts the car when the slug hits the road, launching the car over.
Revealing mistake: When the two police cars flip over if you look close you can see that at least one of the people in the car is a dummy. The one dummy is wearing a hat that appears to stay on his head even when the car flips. (01:03:00)
Revealing mistake: When Jim is at the first gas station trying to reach a phone, he walks outside and John crashes through the garage at the side, if you slow it down you can see that the door to the garage is made with cardboard or paper, or some other soft material. (00:21:20)