- Billing Displacement: Despite receiving second billing, Peter Finch does not appear until more than halfway through the film.
- Creator's Favorite Episode: This was one of Audrey Hepburn's favorite of her films. It was also one of her most financially successful.
- Irony as She Is Cast: The cast and crew included few if any Catholics. Fred Zinnemann was Jewish. Audrey Hepburn and Edith Evans were Christian Scientists. The film's writer, Robert Anderson, was a Protestant, and Peggy Ashcroft was agnostic.
- The Other Marty: Yves Montand was originally cast as Dr. Fortunati but was replaced by Peter Finch before filming began even though Montand's casting had been widely reported in the press.
- Real-Life Relative: Audrey Hepburn's brother, Ian made an appearance in the movie. In the Beginning, Gabrielle took off her ring, put it on top of a letter, and a portrait of him in a silver heart-shaped photo frame.
- Referenced by...: There is a Shout-Out to this film in the 2017 film Novitiate. The postulants are discussing what brought them to the convent and one says "Audrey Hepburn," explaining that she looked so holy, beautiful and perfect in The Nun's Story that she wanted to be like her.
- Orphaned Reference: The original theatrical trailer for the film contains a brief shot of Gabrielle and her father sitting at a café. The shot is an excerpt from a scene that was removed from the final cut. The scene is alluded to in the final film when Dr. Van Der Mal mentions a restaurant reservation at the beginning of the film. Zinnemann removed the scene because he felt it was redundant and hindered the pace of the film's opening.
- What Could Have Been: The role of Sister Luke was suggested for Ingrid Bergman but Bergman herself said she was too old for the role and instead proposed Audrey Hepburn.
Trivia / The Nun's Story