Diagnosis Murder - Headphones
When they are all in the basement, looking for the ghost, a door flings open or something, and the guy with the electromagnetic detector thing says he's picking up some signals. He isn't wearing the headphones. The camera shifts to someone else for a few seconds, then back to tech-head man. He has his headphones on perfectly.
The very last episode, "The Blair Nurse Project"
on 01-04-2002 and