The "EB" referred to in the title means "earth born" according to the original script writer.
Upon seeing this film, George Lucas' father, George Sr., was finally convinced that his son, who became a film student over his desire that his son join him in his stationery business, had made the right choice of a career path.
In one scene, a reel is shown spinning, to segue into another shot. On this reel is a white label that says "University of Southern California".
The title character is always referred to by his full name spoken one character at a time: either 1) Tee, aich, eks, one, one, three, eight, four, ee, bee - 2) the "one, one" spoken as "eleven" or "one, one" is apparently incorrectly spoken as a single "one" In the remake he is usually called just "Thex" as a phonetic pronunciation of the THX prefix.
While attending film school at USC, a professor told the class that George Lucas' first 15 min short film's title, "Electronic Labyrinth: THX-1138 4EB," was inspired by the film class he created it for while at USC: "The Thomas Horton Experience (THX)." The film was produced and distributed by USC, proving the short was created for said film class in 1967 before it was made into a feature film in 1971.