Disney's original film and its sequels include examples of:
Cats Are Evil: Walt Disney naming Lucifer, well Lucifer, was because he didn't like cats as implied by the name.
Dueling Movies: In 1950, a Spanish animation company called Estela Films also released an animated version of the Cinderella story, called Erase una vez.... Disney obviously won, with the former being a lost film.
Supposedly, Disney was aware of the Spanish film and copyrighted the name Cinderella/Cenicienta in Spain, so they could not use it for their film's name.
Prince Charming originally had more screentime. In a deleted scene, he was seen apparently hunting a deer, but it turned out they were friends and playing a game together, and in another, he's reintroduced to Cinderella after she fits the slipper. While surprised that she was a servant, he accepted her immediately.
The 1957 production of Rodgers and Hammerstein's version contains examples of:
Blooper: During a reprise of "Do I Love You Because You're Beautiful?", the camera closes up on Queen Constantina preparing to sing a line, but Prince Christopher interrupts. Jon Cypher apologized to Dorothy Stickney later that night.
Hey, It's That Girl!: Julie Andrews played Cinderella eight years before starring in the film version of Rodgers' and Hammerstein's The Sound of Music. King Maximilian's actor, Howard Lindsay, also happened to become co-writer of the original Broadway version of Sound of Music.
Missing Episode: People living on the East Coast saw the musical live in color, while those in the west saw a black-and-white kinescope. The DVD only contains the latter version.
The 1965 remake of Rodgers and Hammerstein's version contains examples of:
Dubbing singers Bill Lee note the singing voice of Captain Von Trapp in The Sound of Music and Betty Noyes note the uncredited singer of "Baby Mine" from Dumbo play townspeople during the "Prince Is Giving a Ball" number.