John Garfield, a method actor, tried to obtain an emotional bond with the character Joan Crawford played by looking deeply into her eyes which very much unnerved Crawford, who told the director: "Tell him to stop looking at me!"
For the scene where Helen fell off the horse, Joan Crawford claimed she performed the stunt herself, and, relieved it had gone well, she nevertheless was forced to do the stunt again when it was decided Paul's (John Garfield) rushing over and laying on top of her was too racy. It was re-shot, and instead, Helen lay on top of Paul. Crawford later remarked: "I couldn't really understand what was the difference, him on top of me or me on top of him. Well, the difference was I had to fall off the horse again. I did, and I lived to tell the tale." An HD freeze frame tells the truth: it was a stunt double who falls off the horse. (It has been a major point of dispute for decades whether both actors were played by doubles for the coming off her horse scene.)
John Garfield's violin performances are played by two professional violinists standing on either side of him, one to bow and one to finger. The actual music was performed by Isaac Stern. In his autobiography, "My First 79 Years" (New York: Knopf, 1999; page 51), when the movie showed closeups of the hands alone playing the violin (without Garfield in the frame), those are the hands of Isaac Stern.
Oscar Levant, who played Sid Jeffers, was a celebrated pianist, and it is his piano playing that is on the soundtrack.
In 2013 on Piers Morgan Tonight (2011), to promote his autobiography, Robert Blake related that when he was playing John Garfield as a boy in this film, there was a scene he could not get right. Garfield cleared the set and directed Blake himself. After the scene was finished, Garfield told the nine-year-old. "Robert, remember this for the rest of your life. Your life is a rehearsal. Your performance is real."