Almost from the moment Casablanca became a hit, talk began of producing a sequel. One titled Brazzaville (in the final scene, Renault recommends fleeing to that Free French-held city) was planned, but never produced. Since then, no studio has seriously considered filming a sequel or outright remake. François Truffaut refused an invitation to remake the film in 1974, citing its cult status among American students as his reason. Attempts to recapture the magic of Casablanca in other settings, such as Caboblanco (1980), "a South American-set retooling of Casablanca", Havana (1990), and Barb Wire (1996), set in 2017, have been poorly received.
Stories of a Casablanca remake or sequel nonetheless persist. In 2008, the Daily Mail reported that Madonna was pursuing a remake set in modern-day Iraq. In 2012, both The Daily Telegraph and Entertainment Weekly reported on efforts by Cass Warner, granddaughter of Harry Warner and friend of the late Howard Koch, to produce a sequel featuring the search by Rick Blaine and Ilsa Lund's illegitimate son for the whereabouts of his biological father.
The novel As Time Goes By, written by Michael Walsh and published in 1998, was authorized by Warner. The novel picks up where the film leaves off, and also tells of Rick's mysterious past in America. The book met with little success. David Thomson provided an unofficial sequel in his 1985 novel Suspects.
There have been two short-lived television series based upon Casablanca, both considered prequels. The first aired from 1955 to 1956, with Charles McGraw as Rick and Marcel Dalio, who played Emil the croupier in the movie, as Renault; it aired on ABC as part of the wheel series Warner Bros. Presents. It produced a total of ten hour-long episodes. Another, briefly broadcast on NBC in 1983, starred David Soul as Rick, Ray Liotta as Sacha, and Scatman Crothers as a somewhat elderly Sam. A total of five hour-long episodes were produced.
There were several radio adaptations of the film. The two best-known were a thirty-minute adaptation on The Screen Guild Theater on April 26, 1943, starring Bogart, Bergman, and Henreid, and an hour-long version on the Lux Radio Theater on January 24, 1944, featuring Alan Ladd as Rick, Hedy Lamarr as Ilsa, and John Loder as Victor Laszlo. Two other thirty-minute adaptations were aired: on Philip Morris Playhouse on September 3, 1943, and on Theater of Romance on December 19, 1944, in which Dooley Wilson reprised his role as Sam.
Julius Epstein made two attempts to turn the film into a Broadway musical, in 1951 and 1967, but neither made it to the stage. The original play, Everybody Comes to Rick's, was produced in Newport, Rhode Island, in August 1946, and again in London in April 1991, but met with no success. The film was adapted into a musical by the Takarazuka Revue, an all-female Japanese musical theater company, and ran from November 2009 through February 2010.
A spoof of this film is shown in The Muppets Go to the Movies where Kermit the Frog is saying his goodbyes to Miss Piggy. The Sesame Street segment "Great Movie Classics" showcased a spoof of this film in 1990. In this version, Rick keeps telling the pianist to keep saying the alphabet ("Say it again, Sam"). A PBS Kids Ready To Learn segment featured Grover at the piano and Cleo Lion (of Between the Lions) reminiscing the "rhyming game" in 2007.
Casablanca was part of the film colorization controversy of the 1980s, when a colorized version aired on the television network WTBS. In 1984, MGM-UA hired Color Systems Technology to colorize the film for $180,000. When Ted Turner of Turner Entertainment purchased MGM-UA's film library two years later, he canceled the request, before contracting American Film Technologies (AFT) in 1988. AFT completed the colorization in two months at a cost of $450,000. Turner later reacted to the criticism of the colorization, saying, "[Casablanca] is one of a handful of films that really doesn't have to be colorized. I did it because I wanted to. All I'm trying to do is protect my investment."
The Library of Congress deemed that the color change differed so much from the original film that it gave a new copyright to Turner Entertainment. When the colorized film debuted on WTBS, it was watched by three million viewers, not making the top-ten viewed cable shows for the week. Although Jack Matthews of the Los Angeles Times called the finished product "state of the art", it was mostly met with negative critical reception. It was briefly available on home video. Gary Edgerton, writing for the Journal of Popular Film & Television criticized the colorization, "... Casablanca in color ended up being much blander in appearance and, overall, much less visually interesting than its 1942 predecessor." Bogart's son Stephen said, "if you're going to colorize Casablanca, why not put arms on the Venus de Milo?"