Moe Anthropomorphism: Nearly every robot in the movie has a piece of humanization fanart lurking on DeviantArt somewhere. M-O, whose name should already be a direct indication about this. Andrew Stanton even admitted that they "turned up the cute dial too much" with this character.
Elissa Knight recorded the lines for Eve just to give the directors something to work with until a more famous voice actress was contracted, but they liked her performance so much that they kept it in.
The use of Also sprach Zarathustra in a climactic scene was originally put in as a joke, until the filmmakers saw a test audience member pumping his fist in triumph. They left it in.
Real-Life Relative: Benjamin A. Burtt, who was a sound effects apprentice on the film, is the son of sound designer Ben Burtt.
Spell My Name with an "S": How many different ways can you write "Buy n Large"? According to the Pixar Wiki, the former is correct. It was "Buy n' Large" shortly after the merging, but it lost its apostrophe with time; shortened to BnL. However, just on this Wiki, you'll find:
Buy N Large
Buy n' Large
Buy N' Large
Buy 'n Large
Buy 'N Large
Buy 'n' Large
Buy 'N' Large
Buy and Large
Talking to Himself: Ben Burtt provides the voices for both WALL-E and M-O.note Not counting "Foreign Contaminant"
Technology Marches On: If you look closely at the HAN-S robots, their display shows one of the sample images from Windows XP.
According to the commentary, it was originally planned to avert Eternal English (it is 700 years into the future) and have the humans on the Axiom speak a language altered to the point of being unintelligible to viewers. Basically, the sounds-as-dialogue-replacement would have been through the whole movie.
In the original cut, WALLE and EVE's roles in the garbage airlock were reversed so that EVE was the one who was shocked by AUTO, and WALLE had to come to her rescue and fix her. However, Andrew Stanton found himself highly dissatisfied with the scene because of how disconnected it was from the rest of the film, and felt that swapping their roles would simultaneously showcase EVE's Character Development and raise the stakes of the final act. Mind you, this decision came about during a film screening in Poland, meaning the movie was practically finished before the change was made at the last minute, narrowly putting this trope into effect.
On that note, when WALLE's body falls out of the Holo-Detector, the original plan was that he'd be leaking oil, and if the storyboards are any indication, he'd eventually be lying in a small pool of it. This detail is present in the junior novelizations, storyboards, and scripts. It's likely it was removed because it looked a little too much likesomething else.
The humans were once green alien blobs. Stanton and the staff did not find them very identifiable and they evolved into globby humans. By the final product, the humans were evolved into the more into baby-types. Also, the Axiom was a fleet of ships that could attach/detach.
Auto was once a typical moving droid rather than the steering wheel of the ship.
According to the commentary, the Hello, Dolly! songs were originally generic French cabaret music, but Andrew Stanton remembered that his previous film had beaten out another film with French cabaret for the "Best Animated Feature" Oscar, had recently watched the film and became a fan of it, and changed it so as not to seem like a sore winner.
Captain McCrea was a lot more slovenly in an earlier draft and readjustments were done to make him seem more unchallenged rather than dumb.
This is the first new Pixar film to use the new standard 2006 Walt Disney Pictures logo with the excerpt of Pinocchio's "When You Wish Upon A Star" in place of the custom Pixar/Walt Disney Pictures logo with the sky-blue background; WallE is the first film to start production and be released past the end of the original distribution agreement between Disney and Pixar. This agreement was extended to Ratatouille, but Disney's purchase of Pixar invalidated it immediately.
The follow-up DVD/Blu-ray release was the second-highest selling animated DVD and the third highest-selling DVD period of 2008. This specific DVD is the first Pixar DVD to use the Tinker Bell Disney DVD logo prior to the film; all DVDs between the 2000 releases of the first two Toy Story films (which used the 1992 Gold Walt Disney Home Video logo) and this one had no Disney DVD logo on them.