Visible crew/equipment: The very first shot after the opening titles shows cars driving in front of the bar. If you look at a brown car that drives past, you can see the director sitting in the director's chair, reflected on the car.
Revealing mistake: As Sam tells Diane about the guy from Baltimore, the camera starts to pan around the bar. Just as the camera goes past the women's bathroom, the door starts to open. The door then closes itself in an instant frame.