Gregory Peck later said regarding Robert Mitchum, "I had given him the role and had paid him a terrific amount of money. It was obvious he had the better role. I thought he would understand that, but he apparently thought he acted me off the screen. I didn't think highly of him for that."
Gregory Peck, who produced the film, didn't like the original novel's title "The Executioners". When thinking of a new title, he decided that movies named after places tended to be very successful, so he looked at a map of the U.S. until he happened upon Cape Fear in North Carolina.
The financial failure of Ein Köder für die Bestie (1962) ended Gregory Peck's company, Melville Productions.
Prior to its release, the film was heavily censored with many key elements of the fight scenes removed. Also deleted were numerous implications that Cady planned to sexually assault and then tortuously murder both Peggy and Nancy. These deletions were never restored.
J. Lee Thompson had always envisioned the film in black and white prior to production. As an Alfred Hitchcock fan, he wanted to have Hitchcockian elements in the film, such as unusual lighting angles, an eerie musical score by Bernard Herrmann, closeups, and subtle hints rather than graphic depictions of the violence Cady has in mind for the family.