Many people know that the film is based on a book, and said book has many other adaptations and even sequels!
But fewer know of the troubled history of the film.
Walt Disney always wanted to do Alice in Wonderland, even when he made black and white short films in the 1920s. His first attempt was as far back as 1932, but was soon cancelled because of Paramount's version of the film.
The 1933 version was a flop, causing people to doubt weather such a fantastical world and characters could feasibly translate to live-action until The Wizard of Oz (1939) somewhat quenched these doubts and proved somewhat of a success, but still beat out by other films.
Around 1938 and the success of Snow White and the Seven Dwarfs, Walt Disney proposed another version of the film. Storyboard artist David Hall drew hundreds of beautiful images, and Al Perkins wrote a script close to the original book. However, World War 2 shelved these plans.
Disney were bought by the military and used to make war films. Some, like Der Fuhrer's Face, were standard Disney fare with a heavy war motif, similar to what Warner Bros. MGM, and other companies were also doing. Eductaion For Death is a quite dark and somber tale about how Nazis are trained. The vast majority, however, were shorts intended for soldiers only that never got released to the public. After the war, Disney decided to start from scratch and abandon Hall's work, and I can understand why, for Hall's art: while beautiful, is incredibly grotesque:
The population of Wonderland, including the humans, were drawn as wrinkly, fish-eyed, sharp-toothed little horrors. In my opinion, the Cheshire Cat above is even more horrific than the original book, Tim Burton's vision or even the one from American McGee's Alice. All of those versions at least looked somewhat friendly. This version just has an inhuman, predatory malice to his toothy grin and glassy eyes, not to mention his disturbingly HUMAN lips. Not only were these early designs monstrous as all-get-out, they were incredibly difficult to animate due to the sheer detail. That wasn't the only problem though: the script took a much darker tone than the final version, or even more modern revisions like American McGee's Alice.
The first draft was a live-action/animation hybrid. plans were eventually shelved in favor of an all-animated version, the one we have today. Originally, the film had several characters from the books that didn't show up in the final version, like the Gryphon and Mock Turtle, the Jabberwocky, the Dutchess, the White Knight, and others. These characters were cut for time. In addition, they combined Pat with the Dodo, and added the Doorknob. Some of these deleted characters even had songs written for them!
Speaking of songs, Alice in Wonderland has a total of 14 songs, the most in any Disney film. However, dozens of others were cut from the film for one reason or another. One, Beyond the Laughing Sky, later wound up as "The Second Star To The Right" in Peter Pan.