Pixar Planet notes a few of the Easter Eggs found in Cars 2.
This one is apparently in every film.
NOD TO THE NUMBER ? The number A113, which refers to John Lasseter, Brad Bird, Pete Docter and Andrew Stanton?s former classroom at CalArts, makes an appearance in every Pixar film. In ?Cars 2,? you can see A113 in two places: as the number on Mater?s license plate, and as the number on Siddeley the spy jet?s tail fin.