In the book, Elio is 17 years old and Oliver is 24. Timothée Chalamet was 20 years old when the film was shot, while Armie Hammer was 29. The film is set in Italy, and the age of consent in the country is 14.
In September 2016, James Ivory revealed that Shia LaBeouf went to New York to do a reading for the film, and according to Ivory, he was great. But as time passed, LaBeouf had various troubles, so the production company felt they couldn't wisely go with him. Ivory thought they could have, but the production company didn't think so.
In an interview with the website Creative Screenwriting in May 2017, James Ivory revealed that initially, he and Luca Guadagnino would co-direct the film. The rights to the novel were optioned by some friends of Ivory who live in upstate New York, one of them was an agent in Hollywood and the other was then a would-be producer. They asked Ivory whether he would be interested in being an executive producer on a film adaptation of the book if they were able to get it going, and Ivory agreed. Time passed, and they weren't able to get it going because they couldn't find anyone to direct that had a track record. Then they found Luca Guadagnino and he made the suggestion that he co-direct the film with Ivory. They asked Ivory if he would be willing to co-direct it with Guadagnino, and though he didn't really know him, Ivory said, "Sure, but if I do that I want to have my own screenplay." Ivory didn't want anybody else writing the screenplay if he were co-directing and he spent nine months writing it, and because of the screenplay they were finally able to raise the money to make the film. But the French financier thought that it would be awkward to have two directors working together, so Ivory sold the rights to the screenplay to Guadagninos company and they made it.
Armie Hammer and Timothée Chalamet did not have to do a chemistry test for this film. Director Luca Guadagnino does not make chemistry test for his films and thought the two actors were going to be cool between one another.
Armie Hammer and Timothée Chalamet didn't have to audition for the film. Chalamet was cast in 2013, after his agent introduced him to director Luca Guadagnino. When Guadagnino decided to do the film years later, he called Chalamet. Guadagnino cast Hammer after "falling in love with him" when the director saw him in The Social Network (2010), as he told Out magazine in October 2017.
Sufjan Stevens wrote two original songs for the film when only one was requested. The songs are "Visions of Gideon" and "Mystery of Love". Stevens was asked to remake his song "Futile Devices" (from the album The Age of Adz), with piano to be close to Elio.
The trivia item below may give away important plot points.
Director Luca Guadagnino told The Hollywood Reporter that he wasn't interested in including explicit sex scenes in the film, the tone would've been very different from what he was looking for. He wanted the audience to completely rely on the emotional travel of these people and feel first love. He didn't want the audience to find any difference or discrimination toward these characters.