Ezra Miller was originally envisioned to play James Linton. Due to scheduling conflicts, Miller was eventually cast to play a younger version of Salvador Dalí, while Christopher Briney was cast as Linton.
In a 2023 interview with Above the Line, Mary Harron spoke about how she came to make the film and what she thought was important to emphasize in the story: "Edward R. Pressman, who, rest in peace, passed away a few months ago, had done American Psycho (2000) with [me] and The Moth Diaries (2011), [and] every so often, he would send me a script. In this case, he had this project, and there had been several scripts about the idea of Salvador Dalí in the '70s when he was living at the St. Regis Hotel. Though I loved the idea of Salvador Dali in the '70s, I just didn't want to do another film about an artist. I wasn't really interested in the story that was being told in those other scripts, and then Ed called again and again, so I said to John Walsh, my husband, who wrote the script, 'They keep writing me about this. Look at this material, and let me know what you think.' He wrote a memo that really became the basis of the script [and] sort of transformed my feeling about it, which was about focusing on a couple [of] things.
One, this should be a film about a marriage - an extraordinary marriage. Gala Dalí, in the other scripts that have been written on the subject, was just a very small part of it. John said she's fascinating, and she should be a major figure in this, so it's about the marriage, and it's about two extraordinary people after sort of 50 years together, facing old age and death, and their [fear] of both. And then, how Dalí, because of this fear, was spinning and spinning and creating these parties and these amazing distractions.
Very early on, there's this film, [about] which John found an interview [that] Dalí gave, an interview for Spanish TV or a documentary, where he had given this statement, 'It makes every moment of my life become a tremendous pleasure because death is always there waiting to catch me.'
What he was saying was that life becomes incredibly intense. I think that what we loved about Dalí was the way that he did live so intensely, even in his 70s. He's living life and [making] art and [indulging in] work and parties extremely intensely, which is exciting. It's like every day he wakes up, the world is new for him. We liked that about him."
When driving in the car Gala told James, that Walt Disney (she called him "That man with that stupid mouse") wanted to make a movie with Dali. The movie in question is Destino (2003), which Dali and Disney started to make in 1945 but was finalized, completed and released only in 2003, 14 years after Dali's death. It was rediscovered by Disney's nephew Roy Edward Disney, after "Fantasia 2000" was released in 1999 and it inspired him to finish the aborted project.