Revealing mistake: In the car chase scene where the cop is after Roland, you can see that there is no key in the ignition of the cop's car.
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 Lazarus and Klepper's vehicle goes through the wooden crates and flips over, you can see the wooden ramp used to launch the car.
Revealing mistake: When Danny DeVito brings home the 'bigger dog' he says for the new dog to go eat the little dog that always bothers him. He lets the dog go and the dog goes after the little one. But when they show the dog chasing the little one he almost runs right past him. There must have been a trainer on the other side of the set calling the dogs to come over because he wasn't chasing the little dog. (00:40:30)