Continuity mistake: In the lab scene near the end, when Monk has the electric wheel chair, Natalie is holding the bottle of pills in her right hand and the drink in her left hand when she gets up from the seat. In the next shot she is holding the drink in her right hand and the pills in her left.
Continuity mistake: When Monk is trying to get out of the Captain's car, Randy is trying to get his wheelchair out of the trunk. In the shots from the rear of the car, Randy is directly behind the vehicle. In the shots from the front, Randy is a few feet away. (00:18:00 - 00:19:00)
Continuity mistake: In "Mr. Monk On Wheels," after Monk gets out of the car, when he closes the door while standing on his unshot leg, he's facing the front of the vehicle. In the next shot, from behind the car, he's facing the rear of the vehicle without having turned around. (00:18:55)
Continuity mistake: Monk eats a sandwich with a slice of one of the square tomatoes on it, however, in "Mr. Monk Goes to the Asylum," tomatoes are one of his allergies.
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.