Writer-director Celine Song's name appears as the playwright on the poster outside John's theatre production in the film, because the play shown is a real one she wrote in 2016.
Chris Evans admitted that John's shabby apartment and obnoxious roommates mirrored his own memories from his early acting years.
The conception of the film began about ten years before, while Celine Song worked for roughly six months at a professional matchmaking service.
While Lucy and Harry's apartments were filmed on location, John's apartment was built in the studio. Celine Song shared photographs of a home where her husband Justin Kuritzkes had formerly lived as a reference for its dilapidated look.
John Magaro voices the unseen character "Mark P" in the film. He also played Arthur in Celine Song's Past Lives (2023).