Mr. Monk Gets Stuck in Traffic - S3-E13
Revealing mistake: The VW Beetle that slides out of the dump truck and rolls over is noticeably not the same car the victim was driving earlier. It's a lighter color, and is already badly dented, even before it's wrecked.
Mr. Monk Gets Stuck in Traffic - S3-E13
Revealing mistake: When we see a shot of Steve in his car while in the dump truck, it's shot in a studio and the shot is reused each time we see Steve in the car. The shadow is completely different and at one point, when they show Steve in the car with the car and truck bouncing around, you can tell the image is just shaken, rather than the dump truck actually bouncing. There are loose chains hanging off the inside walls that don't move or sway at all.
Answer: Notice also that in the opening credits scene when he is touching parking meters her also wipes his hand on his clothes each time he does it.