After River gets his car washed he rolls down his windows to pay; there aren't any water streaks when he rolls it up - as there would be if the car has actually been washed.
When River and Ira return to the hospital near the end to see Merton, there is an extra in the hallway pretending to clean the floors. She moves the cleaner back and forth a few times, but tilted up an inch above the floor.
While in the elevator, when River and Crissie are discussing his psych report, the camera is visible in the reflection from the steel doors.
When River quickly exits the car wash, he almost hits another car and is honked at by the driver driving down the street. As evidenced in the next shot, that car is going the wrong way on a one-way street.