Cash Cow Franchise: Oh yes! What makes this even more annoying is that some people buy the stuff to look Goth or Emo, not because they've actually seen the movie. Ironically, Tim Burton seemed to try to prevent this to an extent, by refusing to do sequels and ruin the integrity of the movie for fans.
Christmas Creep: This was the inspiration for Tim Burton's poem. He wrote the original story after seeing Christmas decorations being put up in a store window display while the Halloween decorations were being taken down.
Development Hell: Burton used to be a Disney animator and came up with the concept, presented as a poem, in the early 1980s.
Doing It for the Art: Took over three years to film, utilizing up over a dozen sound stages, a phenomenal amount of space. It was also a technical innovation: a special motion-control camera was created to allow for more sweeping cinematography.
Executive Meddling: Technically, this is why the film exists at all. Burton wrote the poem during his tenure at Disney, who, as per their policy, claimed it their intellectual property.
The vampires playing hockey at the end of the film were originally using Burton's head as a puck.
Disney moving the film under its Touchstone label rather then releasing it under the "Walt Disney Pictures" label due to the dark content. Future re-releases, both home and theatrical, would bring it back under the Disney name, after the Disney brand began to expand their demographic starting with the PG-13 Pirates of the Caribbean series.
Spiral Hill: The hill where Jack gets his first song and where Jack and Sally have their Big Damn Kiss. The English localisation of Kingdom Hearts II calls it "Curly Hill" (the Japanese version calls it "Spiral Hill"), but if this poll is any indication, fans massively prefer "Spiral".
Non-Singing Voice: Danny Elfman does the singing voice of Jack, while Chris Sarandon does the speaking voice. In Oogie's Revenge, the trope is averted with Sarandon singing the songs.
The Italian dub manage to avert this with Jack, having him dubbed by Renato Zero, a famous singer; as well as the German dub, with Nina Hagen as Sally.
Recursive Adaptation: The film was based on an illustrated poem by Tim Burton. An anniversary edition of the poem added some more Burton illustrations more close to the film.
Production Posse: Tim Burton regulars like Catherine O'Hara, Glen Shaddix and even Danny Elfman have voice roles.
Talking to Himself: Averted. Elfman does the voice of Jack Skellington and Barrel, but since he's the singing voice of Jack, he never runs into this trope. Likewise averted by Sally and Shock, who are both voiced by Catherine O'Hara but never share a scene with each other.
Originally, Dr. Finklestein was going to be Oogie, disguised because he was jealous that Sally chose Jack over him and wanted to teach her a lesson.See here.
The line "You meddlin' stick figure!" was pretty funny.
Another idea was to have the bugs exit Oogie Boogie's body and attack Jack. The storyboards for this can be viewed here.
Also This early script shows some changes, like we were going to see some of the other holidays at the beginning sequence, and "This Is Halloween" is considerably different from the final product (for example, Jack was going to come in on a CoolUndead Horse).
There was also a couple of storyboards floating about the net (which seems to missing now) that had Jack and Oogie going at each other with freaking maces.
Weirdest of all, the movie almost didn't get the Spiral Hill which codified Goth Spirals! On the DVD commentary, Henry Selick indicated that Tim was unsure about the hill because of his mandate that "magic does not exist in Halloween Town." (Specifically, the unwinding part seemed like magic.) Selick only changed his mind by saying, "All right, then, it's a mechanical hill."
He used this same trick to get Lock, Shock, and Barrel's bathtub worked in, by adding a crank in the back and calling it mechanical.
The poem in the opening narrative was recited by Edward Ivory, who also played the voice of Sandy Claws. An earlier recording (which is available on the original soundtrack) was several lines longer and read by Patrick Stewart. Hear it in all its glory here.
Stewart also provided a coda that wasn't used, where it was revealed that the narrator was in fact Sandy Claus himself, and had visited Jack years later, having "grown quite fond of that skeleton man". It is also revealed that Jack had several baby skeletons running around (presumably with Sally). This verse is also available on the original soundtrack, and can be heard here.
At one point Burton considered making a follow-up titled The Unlucky Clover based around St. Patrick's Day.