Marlene Dietrich's from-the-back cameo in the film is due to her stopping by on a break from filming The Flame of New Orleans to visit her then-boyfriend, Broderick Crawford. She graciously volunteered to fill in for Claire Dodd in a non-dialog scene after the actress left the studio for the day.
Broderick Crawford's line "He thinks he's Sherlock Holmes" is a gag. At the time this was made, Basil Rathbone had already played in two Holmes films, "The Hound of the Baskervilles" and "The Adventures of Sherlock Holmes."
Associate producer Burt Kelly was tasked with delivering both this film and "Oh, Charlie" (released as Hold That Ghost) nearly simultaneously.
Both Broderick Crawford (replacing Richard Carlson) and Basil Rathbone (replacing Paul Cavanaugh) were late casting changes. Production was delayed nearly a month to accommodate these changes and other production scheduling problems.
Director Orson Welles saw "The Black Cat" and was so impressed by cinematographer Stanley Cortez's atmospheric lighting and angling that he hired Cortez to photograph The Magnificent Ambersons which is also set largely inside a Victorian-era mansion.
Fans of Universal films of the 40s will recognize the interiors and exteriors of the Winslow Mansion, which would be utilized in such subsequent Universal releases as "The Night Monster," "The Mummy's Tomb," "The Mummy's Ghost," and "Son of Dracula."
In the trailer, 'Broderick Crawford' is credited as "Brod Crawford".
The "Universal Horror Classic Movie Archive" DVD boxed set release of this film includes a reissue trailer from Realart Pictures that moves 'Alan Ladd''s billing up to second (after Basil Rathbone) to take advantage of his later stardom at Paramount.
Universal ordered Alan Ladd's billing increased to take advantage of his notoriety in the current Paramount hit This Gun for Hire.