Actor Allusion: Danny's "oh, I've been known to twinkle a toe or two."
Box Office Bomb: It made $22 million at the box office, enough to earn back its budget (which was somewhere in the $15-20 million range), but a very weak take compared with all the hype the film had gotten, plus the soundtrack album going double platinum and spawning some big hits. Several careers were damaged in its wake.
Breakaway Pop Hit: "Magic", "Suddenly", and the title song. "Magic" was a hit to the point where most people who have heard it have no idea it was originally from a motion picture soundtrack.
Genre-Killer: The movie's failure nearly killed the musical as a creditable genre.
Money, Dear Boy: The reason for Gene Kelly's involvement. That and the job was close to his home. Still, Gene Kelly has stated that working with Olivia Newton-John was great.
Non-Singing Voice: Michael Beck doesn't sing in this movie. He was dubbed by Cliff Richard.
For Electric Light Orchestra, who wrote and performed several of the songs. Jeff Lynne eventually came to terms with it, though, and released an album with rerecorded Xanadu tracks.
And for director Robert Greenwald, who's more recently made a name for himself as a left-wing muckraking documentary director (Outfoxed: Rupert Murdoch's War on Journalism, Wal-Mart: The High Cost of Low Price).
Release Date Change: Joel Silver, Robert Greenwald and Victor J. Kemper wanted more elaborate special effects, but that became impossible when Universal Pictures moved the release from Christmas 1980 to summer 1980.
Star-Derailing Role: The film was meant to launch Olivia Newton-John's career as a solo star. Due to its complete failure at the American box office, it became the one and only time she received top billing without a co-star in a theatrical release. As for Michael Beck...
Vindicated by Cable: The movie was trashed by critics but it picked up its core audience on pay cable channels. Especially in the early 80s era, when HBO (which until 1981 didn't even operate on a 24-hour schedule) had a very small library of movies to air.