Like most movies, a mistake is made with the sound of the revolver. It will not make the "clicking sound" until is has engaged the ratchet pawl within the gun. So while the cylinder spins outside the gun, it shouldn't be making the sound it makes.
The original police car in pursuit of the BMW when it flies off the hill is a Chevrolet Caprice. Yet when he tells him to pull over, the police car that is chasing him is a Ford Crown Victoria. But the police car that crashes into a Ford Bronco is the Chevrolet Caprice again.
When the driver approaches the drawbridge, there is no semi on the bridge, or pulling up to it. As he drives away from the edge, an eighteen wheeler is parked in front of the white Ford truck that is seen in the approach shot.