The "Light Cycle" game became a popular arcade game pretty quickly, which is somewhat recursive considering that it itself was based on one of the first arcade games.
Inverted with the TRON arcade game (whose cabinet is briefly seen) which was released just shortly before the movie (and spawned both a sequel and a few home games). The movie received not one, but two arcade games: TRON and Discs of TRON. Discs was originally supposed to be part of the former, but was cut for time. Interestingly, the "Grid Bugs" appear in the game TRON, but only receive a comment in the movie TRON!
Eventually played straight with Space Paranoids, which was released as an online game in 2009.
Deleted Scene: The "love" scene between Tron and Yori, including Yori getting a new outfit before they head for the I/O Tower. Described in detail in the novel.
The director asked Peter O'Toole to play Dillinger... however, he really wanted to play Tron.
On the DVD's "Making of" documentary, they explain that O'Toole bowed out after finding out that the majority of the film would be shot in front of blue-screen (or black, whatever) instead of on sets and locations. Technically, any scenes in the electronic world that had actors in them were filmed on sets. They were just all black with backlit animation added in post-production.
The first band offered to score rock songs for the movie's soundtrack was Supertramp.
Word of God: All of the programs retain their User's personality. For example, Cindy Morgan was told that Yori retains some vague memory of her user (Lora) having a romance with Flynn at one time.