Other: In the opening credits, Bob answers the phone. None of the buttons light up when the phone rings. On that style of phone, the light would indicate which line to answer. The phone is obviously a prop.

Deliberate "mistake": The circular desk where Carol sits should be rotated 180 degrees so she is facing the elevators. How many times have you gotten off an elevator in a fancy office building only to see the back of the receptionist's head?