Humphrey Bogart was originally chosen to play Harold Goff. However, Ida Lupino had just finished shooting They Drive by Night and High Sierra with Bogart, and they had not gotten along. Lupino protested, and because she'd had a bigger name than Bogart at the time, she got her way, forcing an angry Bogart to shoot off a telegram to Jack L. Warner asking, "When did Ida Lupino start casting films at your studio?"
Because Anatole Litvak was a Russian Communist, the leftist slant to "Out of the Fog" stood out to the people at the Hays office, though given the historical context to the times in which this movie was made, it is obviously more anti-Nazi than pro-communist. Nonetheless, the Hays office just had to have their finger in the pie and would not allow the protagonists to kill off Harold Goff, as they had in every performance of the original story, Irwin Shaw's play "The Gentle People," and John Garfield's character had to die accidentally, giving the ending an interesting twist, which, as some critics noted, made the story even better.
For this film, which was based on Irwin Shaw's play "The Gentle People", nearly all of the characters' names were changed from the play.