Bette Davis and William Wyler fought a great deal during filming. Disagreements ranged from Davis's interpretation of the character (Wyler thought she should be more sympathetic) to the appearance of the house (Davis thought it was far too opulent for a family struggling financially), to her appearance (Wyler thought her white makeup made her look like a Kabuki performer.) Davis eventually walked out of production, but returned when she heard rumors she was going to be replaced by Katharine Hepburn or Miriam Hopkins.
Herbert Marshall had lost a leg in WWI. The scene where Horace crawls up the stairs is done by a stunt man. Marshall takes the role until he walks towards the stairs, but is hidden by a curtain for a moment. That was where the switch was made.
William Wyler encouraged Bette Davis to see Tallulah Bankhead's Broadway performance. Davis was not keen on the idea but agreed to do so, regretting it instantly as she realized that she was now forced to play the character in a very different manner. Bankhead played her as a fighter; Davis' interpretation was of a cold, calculating and conniving woman.
For the second straight year, a William Wyler directed Bette Davis vehicle was nominated for Best Picture, Director and Actress at the Academy Awards. (The year before the film in question was The Letter (1940).) And for the second straight year, everyone went home empty-handed.
The original stage production of "The Little Foxes" opened at the National Theater in New York on February 15, 1939 and ran for 410 performances. It starred Tallulah Bankhead as Regina Giddens and featured Dan Duryea as Leo Hubbard. As of this date (Aug. 2008), it has had three revivals, starring Anne Bancroft in 1967, Elizabeth Taylor in 1981, and Stockard Channing in 1997.
David Hewitt, the character played by Richard Carlson, does not appear at all in the play. He was added to provide a love interest for Alexandra Giddens (Teresa Wright's character), and to add another sympathetic male character to the film besides Horace Giddens (played by Herbert Marshall).
William Wyler decided not to open the play out for its film adaptation. This was because he recognized in Regina a character rather akin to a director like himself so he wanted to play it out in as theatrical a manner as possible to emphasize her controlling nature.
'Although rumours were circulating that 'Jack Warner' was looking to replace Bette Davis after she walked off the picture, the truth of the matter was that he was very reluctant to do so as it would involve significant costs in reshooting all the scenes already in the can with a different actress.