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."
Jim Morrison's real grave 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 was stolen sometime in 1988. The grave is also surrounded with a steel fence to prevent further vandalism to the tomb, as pieces of the stone had been chipped off and stolen over the years.
The cave scene, when Jim wanders 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. The state fined Stone and banned future film shoots at the caves.
The bar that Jim and his buddies frequented in the movie is Barney's Beanery, a popular spot in W. Hollywood, California. It was the last place Janis Joplin visited before she died at a nearby hotel later that night.
Val Kilmer broke his arm badly when he performed a jump from the stage into the crowd. The stuntman failed to catch him, leaving Kilmer with an abnormal growth on his right elbow. The growth is clearly visible in Heat, when McCauley discovers Shiherlis sleeping in his living room and begins briefing him on their itinerary.
Billy Idol's role was originally much bigger. Prior to filming, Idol was in a motorcycle accident that left him unable to walk. Every time he appears in the film, he is either on crutches, sitting, or lying down.
Robby Krieger, the guitarist in the Doors, gave his consent and assistance to the film because Stone's earlier film Salvador (1986) was one of his favourite films and he could easily envision a film like that about the Doors.
In the film, the band is signed after being fired from Whiskey-a-Go-Go. In real life, they were signed by Elektra Records on August 18, 1966. Whiskey-a-Go-Go fired the band on August 21, after Morrison used acid induced, profane, Oedipus Rex lyrics.
Because the film was shot out of sequence, Val Kilmer had to carefully gain weight for Morrison's heavier, later years so that the flab was only noticeable on his belly and could be concealed when he played Morrison as a younger man.
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 outfits the band is wearing during the Ed Sullivan performance are actually accurate. The only outfit that was incorrect was Jim Morrison's. Val Kilmer is wearing a black shirt and black leather bottoms. Jim Morrison was actually wearing a white shirt and a leather jacket during the infamous taping.
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. A sculpture of Alexander the Great appears over Jim. Jim Morrison compared himself to Alexander the Great several times in his life. Oliver Stone later directed Alexander (2004), a biography of Alexander the Great.
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. However, the musical version of An American Prayer was not recorded by the surviving members of the Doors until several years after Morrison's death.
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.
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."
Michael Madsen originally auditioned for the role of Jim Morrison. He was later cast in the part of Tom Baker after Billy Idol switched from playing Baker to the smaller role of Cat due to being in a bad motorcycle accident.
Jim Morrison (Val Kilmer) is frequently linked with and even directly called Dionysus throughout the film. In Alexander (2004), Kilmer plays Philip, whose wife (Angelina Jolie) is a devout worshiper of Dionysus.
Val Kilmer and Meg Ryan were also in Top Gun (1986). Incidentally Kilmer worked with director Oliver Stone on this film and Top Gun lead, Tom Cruise worked with Stone on Born on the Fourth of July (1989). What's more Cruise worked with Stone before Kilmer did.
The trivia items below may give away important plot points.
In the scene where Jim falls off the stage in Miami and begings singing "Dead Cats/Break on Through to the Other Side", there is a Native American seen following him dancing around. This person is seen in the film multiple times and is considered to be death.
ALSO A GOOF, At the press conference right after the Warhol Party, when Morrison is speaking about the band. A reporter lifts up a book of Morrison's poems not yet published by himself in 1970 , where and when he has had a short self published run of 100 of each book, "The Lords" and "The New Creatures"