If you happen to take some time to explore the Prop Shop portion of the Backlot Tour, there's lots of old movie props to see and hidden among them all is a reference to the 1988 film, "Who Framed Roger Rabbit?".
These boxes of eye balls are props from the "Who Framed Roger Rabbit?" film finale, where Judge Doom tries to kill Roger Rabbit and his wife Jessica Rabbit. The eye balls are what cause Judge Doom to trip and lead to Eddie Valiant's escape.