A113 is a recurring media easter egg created by alumni of the California Institute of the Arts. The number refers to the classroom used by the graphic design and character animation students.
During the scene where Stitch sets up and destroys the miniature replica of San Fransisco in Lilo’s room, to the right of the screen you can see an A113 license plate meant to model a billboard.
As Nani is leaving General Store after her job interview we see the front and back of a fire truck hummer on it’s way to her house. The license plates read A113.
In order to save Lilo from Captain Gantu, Stitch hijacks an 18-wheel tanker truck which has an A113 license plate.
During the early ending credits when the family photos are being shown, one of them has Stitch on the roof of Nani’s blue VW Beetle shooting water at Nani and Lilo. The license plate of the Beetle says A113 even though earlier in the movie during the Stitch vs Jumba fight scene it was shown to say, “LS 2153”.