Toy Story Midway Mania is filled with references to the Toy Story films, as well as other Pixar related endeavors. Chief among them is it pays homage to Luxo Jr, the lead character in Pixar's first film that it produced back in 1986. Just as Mickey Mouse is a central and key character to the Disney Company, Luxo Jr has emerged as the patriarch of Pixar and the attraction has a few references to the film.
Inside the queue, you'll find the ball that Luxo likes to hop on sitting to the left of the Mr. Potato Head animatronic. The ball is that familiar bright yellow ball with a red star on its opposite sides with a navy blue ribbon around the center.
On the other side of Mr. Potato Head is a lamp that "looks" like Luxo as well. It can't be a coincidence that Imagineers chose to illuminate their star animatronic with a desk lamp, that while not the same color as Luxo, is in a similar pose to Luxo and the same style of desk lamp as Luxo.
There's also another place you can find a Luxo reference inside the attraction and that's after you're done with the ride but waiting to be brought to the area to unload. As you pass underneath the overpass where guests wait in line, on the wall is a drawing of the ball from Luxo in a bin.
I suppose Andy is a big fan of these Luxo balls, or there was a sale on them at some point and he filled up. At any rate, keep an eye out for these Pixar references the next time you're waiting in the queue for Toy Story Midway Mania.