Originally the film credits were to read "Errol Flynn in The Sisters", but Bette Davis demanded equal billing alongside Errol Flynn. She also pointed out that the original credits had an unwelcome sexual connotation.

According to contemporary news reports, Anita Louise hated wearing a corset for this film. Bette Davis didn't mind it quite so much.

Stock footage from Old San Francisco (1927) was used.

In the novel on which the film was based, the character of Louise Elliott ends up marrying a different man in the denouement.

Several people are in studio records/casting call lists as cast members, but they did not appear or were not identifiable in the movie. These were (with their character names, if any): Edwin Brian (Newsboy), Rosella Towne, Susan Hayward, Paulette Evans and Frances Morris (Telephone Operators), John Harron, Lew Harvey, Richard Bond and Mira McKinney. The 4 telephone operators were possibly among a group seen only from the rear and are not recognizable.

The earthquake sequence took three weeks to shoot and cost $200,000 ($3.45M in 2017).

Character actor Joseph Crehan, playing the politician who announces the election returns, is uncharacteristically made up to look like Roosevelt with glasses and a mustache.

This film's earliest documented telecast took place in Tucson Thursday 29 November 1956 on KDWI (Channel 9); it first aired in Portland OR Saturday 20 April 1957 on KLOR (Channel 12), in Bloomington IN Saturday 4 May 1957 on WTTV (Channel 4), and in Honolulu Sunday 26 May 1957 on KHVH (Channel 13).

Preview audiences did not like the original ending where Louise married William as per the novel, so the studio ordered re-shoots.