Adaptation Sequence: Newspaper Comic —> TV show —> Cartoon —> Video Game —> Movie —> TV show loosely based on movie —> Video Game —> Sequel to movie —> Broadway Musical
Beam Me Up, Scotty!: Morticia is often quoted saying, "Normal is an illusion. What's normal for the spider is chaos for the fly." However, no one is sure when exactly she said that.
She does say the line in The Musical, but it seems to be a reference to the presumed earlier quote.
Keep Circulating the Tapes: To this day, there has never been a DVD release for the following Addams Family films and shows: The Addams Family Fun-House, Halloween with the New Addams Family, the 1992 animated series, Addams Family Reunion, and — at least in America — The New Addams Family.
One Normal Night: From the song of the same name in the 2010 Broadway musical, where Wednesday, hoping to set a good impression with her fiance and his family, requests that the Addams clan try to behave like average human beings. As expected, they can't, and Hilarity Ensues.
What Could Have Been: After Illumination Entertainment obtained the rights to Charles Addams' original cartoons, there was a planned stop-motion animated film with Tim Burton calling the shots. As of July 2013, the project has been cancelled.
It was once stated that the first live-action film was originally going to leave it ambiguous over whether Gordon Craven really was Fester or was merely an impostor who subsequently became convinced that he was Fester, but the cast agreed that it would be better if Gordon turned out to actually be Fester all along since it helped with the theme of family. They even went as far as having Christa Ricci be the one to convince Barry to change it.
For the various television serieses:
Dueling Shows: With The Munsters. The Addams family were humans that acted like monsters, but the Munsters were monsters that acted like normal humans. It was an interesting contrast.
The Other Darrin: A sort-of example from the series: the man playing Thing occasionally used his left hand just to see if anybody would notice.
Recycled Script: Most of the episodes of The New Addams Family were recycled from the original series. In fact, the episode "Thing is Missing" is a twofer. Not only is it a remake of an episode from the original show, but it also borrows two plot elements from the 1992 animated series episode "Itt's Over" (though this time, Uncle Fester starts growing hair because he's stressed over the mistaken belief that Thing is dead rather than Cousin Itt).
Throw It In: Ted Cassidy ad-libbed "You rang?" in the pilot, and the producers kept it — and changed Lurch from a mute to allow for it.
Also in Addams Family Values, Cynthia Nixon has a blink-and-you'll-miss-her scene as a Hippie Nanny.
Also also in Addams Family Values, while Fester is waiting for Debbie to return at their bomb-rigged home, Debbie is secretly at a nightclub being wooed by several men. Look closely at the Hispanic-talking one in the sailor's outfit — that's a young Tony Shalhoub.
ALSO also also in Addams Family Values, David Hyde Pierce is the doctor who delivers baby Pubert at the hospital at the beginning, though you can't exactly see him very well due to the surgeon's mask covering his face.
Harmony was a "real girl scout" in the first movie and Little Miss Perfect Amanda in the second. Her father in the second film was Chandler's boss.
Wednesday in Reunion is Wednesday in The New Addams Family - Nicole Fugere was the only actor to appear in both.
The Other Darrin: The third movie did this to most of the actors playing the family, such as having Carol Kane replace Judith Malina as Granny. It's intended as a separate continuity, and the only reason it exists is to have served as the Pilot Movie for The New Addams Family.