The area of Echo Lake that includes Star Tours and Indiana Jones Epic Stunt Spectacular is commonly referred to as "Lucas Land" because both properties are owned by George Lucas, the director and producer of all those films. This fact wasn't lost upon Disney Imagineers and there's a few nods to Lucas, especially his earliest work in a couple of places.
George Lucas' first feature-length film was a science-fiction film called "THX 1138". The film was released in 1971 and was about a future world where everything is controlled by a big brother-esque controlling force. While the film is no where near as popular as "Star Wars" or any of the "Indiana Jones" films, nonetheless THX 1138 was very important to Lucas and he enjoyed making subtle references to it in his films. Imagineers continued that trend as well.
If you're waiting in the queue at Star Tours, you may recall hearing a number of boarding announcements over the loudspeaker and one of them is "Will the owner of a landspeeder with vehicle number THX 1138 please move your vehicle? You're parked in a non-hovering zone." This is of course referencing the film pretty directly.
If you wander over to check out the Indiana Jones Epic Stunt Spectacular, you may stop for a quick snack a the Dip Site snack counter outside the entrance and if there is a long line and you look around as you wait, you'll notice another reference to the film. The Dip Site sign above the counter reads "Dip Site #1138", and yes, the 1138 refers to the THX 1138 film.