Prior to the audition, Val Kilmer memorized the lyrics to all songs written by Jim Morrison. He also sent director Oliver Stone a video of him performing a few Doors songs, which Stone claimed hurt Kilmer's image as Morrison.
The poem that Jim Morrison is reading at the opening of the film is actually two selections from his book of poetry "An American Prayer": "Awake Ghost Song" and "Awake". It is the same book that Jim gives to his bandmates at the end of the film. The musical version of An American Prayer was not, however, recorded by the surviving members of the Doors until several years after Morrison's death.
Prior to production, Val Kilmer lived and breathed Morrison for nearly a year, dressing in his clothes and hanging around at his old haunts on Sunset Strip. Jim Morrison biographer Jerry Hopkins says that he saw him one day when meeting Oliver Stone for lunch, using a payphone in the restaurant, and was so convinced by the believable image he cut that the first thought that entered his head was, "I'd forgotten how tall Jim was."
The film kicked around for nearly twenty years before it made it into production. Amongst other actors considered for the role at various times were Tom Cruise, Jason Patric, and John Travolta. During the time Travolta was being considered he met the band (who were initially quite involved with the possible production), and they discussed reforming the band and going on tour with Travolta on vocals. In the end the band chose not to do this because they felt John Travolta was too nice to fill Morrison's shoes.
Ian Astbury, (lead singer for the band The Cult), was considered for the role of Jim Morrison by Oliver Stone. They had lunch in Hollywood to discuss the role, but Astbury declined the role, stating he (and the surviving members of The Doors) did not like the screenplay. From 2002 until 2007, Ian went on tour with The Doors as lead singer.
After the scene when Jim is being photographed, he stands in place and looks at the camera as a newspapers and magazines fly by showing The Doors' rise to fame, but also, a sculpture of a Greek figure appears over Jim's. This is a sculpture of Alexander The Great. Jim Morrison compared himself to Alexander the Great several times in his life. Director Oliver Stone would go on to direct Alexander about Alexander the Great, starring Kilmer as Alexander's father.
Billy Idol's role in the movie was originally much bigger. Prior to filming, Idol was in a motorcycle accident that left him seriously injured and unable to walk. Because of this, his role in the movie was reduced severely, and you'll notice that when he does appear in the film, he is either on crutches, sitting, or laying down.
The real grave of Jim Morrison is shown at the end of the movie, filmed at the Père Lachaise Cemetery in Paris, France. The headstone has since been changed and the graffiti was removed from the surrounding graves at the request of Jim's parents. The bust of Jim is believed to have been stolen sometime in 1988. The grave is also surrounded with a steel fence to prevent any vandalism to the tomb itself, as pieces of the stone had been chipped off and stolen over the years.
Oliver Stone's then wife Elizabeth is mentioned in the closing credit roll as Naijo No Ko. This Japanese term means "with the help of my wife" or, more colloquially, "I owe my success to my better half".
The graves in Père Lachaise that are shown before Jim's are, in order, Frédéric Chopin, Georges Bizet, Oscar Wilde, Sarah Bernhardt, Honoré de Balzac, Marcel Proust, Gioacchino Rossini, and Molière. All had careers that were representative Jim's career and interests: Chopin, Bizet and Rossini were musicians. Balzac, Wilde and Proust were writers and philosophers. Berhardt and Molière were live stage performers.
Robbie Krieger, the guitarist in the Doors, gave his consent and assistance to the film because Stone's earlier film Salvador was one of his favourite films and he could easily envision a film like that about the Doors.
Jim Morrison (Val Kilmer) is frequently linked with and even directly called Dionysus throughout the film. In Alexander, Kilmer plays Philip, whose wife (Angelina Jolie) is a devout worshiper of Dionysus.
Although in the film the band are signed after being fired from the Whiskey-A-Go-Go, this is not how it actually happened. In reality, they were signed on August 18, 1966 by Elektra Records. On August 21, after Morrison used acid induced, profane, Oedipus Rex lyrics, they were fired from the club (this was portrayed correctly in the film).
Because the film was shot out of sequence, Val Kilmer had to carefully gain weight for Morrison's fatter, later years so that the flab was only noticeable on his belly and could be concealed when he played Morrison as a younger man.
The cave scene where Jim is wandering out in the New Mexico desert was shot at the Mitchell Caverns in the East Mojave Preserve in California. According to the tour guide there, Oliver Stone and the art dept. painted Indian petroglyphs at the site that wouldn't wash off. This upset the state park, Stone was fined, and which prompted that filming unfortunately could no longer be done at the caves.
The bar that Jim and his buddies frequented in the movie is Barney's Beanery, a popular spot in W. Hollywood, CA. This was the last place Janis Joplin went to before she died later that night at a nearby hotel.