The Addams Family and the Spaceman - S1-E27
Other mistake: In this episode, the radio announcer said that the reported spacecraft was seen over the Cemetery Ridge District, and Morticia said "That's our area." However, in "Cousin It Visits The Addams Family" (S1: Ep 20) they are supposedly in the Greenbriar Woodlawn District.
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.
Uncle Fester's Toupee - S1-E31
Other mistake: Bad editing shows up a couple times in this episode. Once when Max goes to ring the doorbell. As he reaches for it, it moves out and in on its own and he moves with it. As he does, its easy to see the film is run back and forth. The second time is when he reacts to the news of Kitty. He flinches, and his toupee slips over his face, then the film is run backwards so it goes back.
Wednesday Leaves Home - S1-E10
Other mistake: As Fester comes into the room where Gomez and Morticia are, the piece of the cactus leaf that Fester is to eat is differently colored than the rest of the leaf.
Other mistake: As Fester goes to shoot Gomez, his aim strays upward to about a 45 to 50° angle. Not enough to shoot the support chain on the light that is directly above him, and hits him on the head.
Other mistake: As Kitty comes down the stairs, Hilliard screams, and Kitty goes back up. It's obvious the film was run backwards.
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