When Christian Bale and Ewan McGregor were filming their sex scene, the director cut without letting them know, so the two continued to simulate the act until they realized the trick that had been played on them.
Courtney Love considered supplying music to the film's soundtrack, however after viewing a rough cut she withdrew, claiming that the character of Curt Wild too closely resembled her late husband Kurt Cobain both in character and physicality. The Wild/Cobain parallel later became a much-discussed point among critics, and while director Todd Haynes and actor Ewan McGregor have noted similarities between Cobain and Wild, both claim the resemblance was unintended. Haynes, for his part, notes that Cobain borrowed many style traits from Iggy Pop, who served as partial basis for the Wild character.
The film was originally supposed to feature some of David Bowie's music, hence the title. However, when Bowie learned that the script for the film was partially based on the unauthorized biographies "Stardust: The David Bowie Story", written by Henry Edwards and Tony Zanetta and "Backstage Passes" written by Bowie's ex-wife Angie Bowie, he threatened the producers with a lawsuit. Hence, no Bowie songs were used, and the script was partially re-written to avoid unnecessary resemblance between Bowie and the Bowie-style character Brian Slade.
The name of Brian Slade's rock persona, "Maxwell Demon," and that of his band, "The Venus In Furs", are references to two of the key artists in the original Glam Rock movement: Maxwell Demon was the name of a band in which Brian Eno performed in England in the mid 60s, and "Venus In Furs" (originally the title of a 1870s novel Austrian writer by Leopold Sacher-Masoch, of whose name the term 'masochism' was derived) is the name of a song by Lou Reed and The Velvet Underground. Songs by both artists are featured on the film's soundtrack.
Toni Collette was cast very late in pre-production and had very stiff competition from several other actresses for the role of Mandy Slade. Director Todd Haynes finally cast Collette after the actress faxed him a personal note that read simply "I AM MANDY SLADE!" Haynes saw this as exactly the kind of thing the character Mandy would do.
During the Festival sequence where Brian sees Curt perform for the first time, Ewan McGregor was only due to moon the disgruntled crowd. But inspired by the antics of Iggy Pop, he improvised, and ended up gesticulating wildly while flashing the audience, leaping about with his trousers around his ankles.
The Curt Wild character is mainly inspired by David Bowie's relationship with two American 1960's underground rockers whose careers Bowie resurrected, 'Iggy Pop(I)' and Lou Reed. Iggy Pop hailed from Michigan and shared Wild's long blond locks, while Reed underwent shock therapy for bisexuality as a teen and was rumored to have had an affair with Bowie before their falling out after Bowie produced Reed's album Transformer. Much central to the film is fictionalized such as the mythical, mysterious decade-long disappearance of "Slade", although he reincarnated himself as Tommy Stone, a blonde with a white suit (the 'thin white duke'). Bowie wasn't as huge of a star as Slade is depicted here and never withdrew for so long from the public-eye as did the film's character.
They wanted to use many Bowie songs for the movie (ten or something). David Bowie did not approve songs to be used, because he had plans of making his own movie, based on Ziggy Stardust. Unfortunately this movie was never made.