The Addams Family Goes to School - S1-E1
Visible crew/equipment: When the phone rings and Thing hands it over to Morticia, the camera zooms out and you can the actor playing Thing quickly hide behind the couch. (00:24:15)
The Addams Family Goes to School - S1-E1
Visible crew/equipment: If you look at the shrubbery, you can see the person performing our first glimpse of Thing moving around.
Morticia and the Psychiatrist - S1-E2
Visible crew/equipment: When Uncle Fester climbs down the tree (after observing Pugsley interact with the shrink, a shadow of the moving dolly mic is visible as it moves backward. (00:22:35)
Crisis in the Addams Family - S1-E24
Visible crew/equipment: In the play room, as Fester goes to leave, the shadow of the boom mic is on the wall behind him.
Uncle Fester's Toupee - S1-E31
Visible crew/equipment: As Gomez goes to ring for Lurch, the shadow of the boom mic is on the wall behind him.
Answer: Basically from what I understand, they stuck the innards of a small flashlight into the base of the bulb and put a little switch on it. When he put it in his mouth and bit down, his teeth would hit the switch, which would turn on the flashlight and made the bulb light up.
TedStixon