The Addams Family Goes to School - S1-E1
Continuity mistake: After Mr. Hilliard goes through gate and nears the house, it's really at the real house. A second later, he's approaching the now-familiar front porch on the studio set. This is easy to tell because the layout of the two porches are radically different.
The Addams Family Goes to School - S1-E1
Audio problem: When Wednesday comes into the house crying her mouth isn't moving.
The Addams Family Goes to School - S1-E1
Audio problem: After Gomez suggests the rack for a stretch, he rings for Lurch. You hear Lurch say "You rang?", but his lips don't move.
The Addams Family Goes to School - S1-E1
Continuity mistake: When Wednesday is first holding her doll, the buttons are facing forward. A second later, it's backwards.
The Addams Family Goes to School - S1-E1
Other mistake: When Thing is first seen, he's a right handed thing. When Wednesday gets the mail from him, Thing is a lefty.
The Addams Family Goes to School - S1-E1
Other mistake: As Gomez and Hilliard come to the top landing, the supposed access behind Gomez at the top of the stairs can be seen to be either a blank wall or a door that should be a hallway.
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.
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)
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