This Easter Egg has made an appearance in nearly every Pixar film ever made. It’s practically the origin source for all Pixar Easter Eggs after that. It is so popular that it can even be found in FX laden films like The Hunger Games: Catching Fire, Mission Impossible Ghost Protocol, The Avengers and Star Wars Episode 1: The Phantom Menace. On TV it appears occasionally on The Simpsons, South Park, Rug Rats, and American Dad. It has even been seen in video games like Prototype and Kinect Rush.
The Easter Egg: The number A113; the Cal Arts Animation classroom that Pixar executive and animators like John Lasseter, Brad Bird, Andrew Stanton, Peter Doctor and Tim Burton attended and studied in. Director Brad Bird started the tradition by putting the number on a car license plate in Family Dog, an animated segment from the 1987 TV series Amazing Stories. Since then it has been a running gag for any production that boasts a large number of Cal Arts Animation Arts alumnus on the crew.
The only Pixar movie without an A113 Easter Egg seems to be Monsters, Inc. Maybe John Negroni, the famous Pixar conspiracy theorist can divulge where it is?
A Bug’s Life
Brave (in Roman Numerals)
Lilo and Stitch
The Brave Little Toaster
The Hunger Games: Catching Fire
Mission Impossible: Ghost Protocol