Audrey Hepburn later admitted she would never have accepted the role of Eliza Doolittle if she had known that producer Jack L. Warner intended to have nearly all of her singing dubbed. After making this movie, Hepburn resolved not to appear in another movie musical unless she could do the singing on her own.
When Audrey Hepburn (Eliza Doolittle) was first informed that her voice wasn't strong enough and that she would have to be dubbed, she walked out. She returned the next day and, in a typically graceful Hepburn gesture, apologized to everybody for her "wicked behavior."
According to one of Sir Rex Harrison's biographers, Alexander Walker, the song "I've Grown Accustomed to Her Face" held special memories for the actor, as during the original Broadway run he used to sing the song to his third wife Kay Kendall, who would stand in the wings watching his performance. Harrison later admitted that when he sang the song in this movie, he was thinking all the time about Kendall, who had died a few years before from leukemia.
When Sir Rex Harrison accepted his Academy Award for this movie, he dedicated it to his "two fair ladies," Audrey Hepburn and Dame Julie Andrews, both of whom had played Eliza Doolittle with him.