Factual error: When Bill Cosby (as a ghost) goes to the doctor and the doctor checks his heart (which is not beating), Bill Cosby then presses play on a tape recording of a sound of a beating heart. The doctor hears this through the stethoscope, even though the tape recorder is behind Bill's back, which is not possible.
Revealing mistake: The bottom of Tony's legs disappear when Elliot emerges from the phone and grabs hold of him.
Continuity mistake: When Diane is driving the station wagon with her father at the start and later after her father's physical exam, in the exterior shots facing the two of them the rear-view mirror vanishes.