The film is based on Pierre Boileau and Thomas Narcejac's novel "Celle qui n'était plus" (She Who Was No More). Alfred Hitchcock also attempted to buy the rights to this novel; Boileau and Narcejac subsequently wrote "D'Entre les Morts" (From Among the Dead) especially for Hitchcock, who filmed it as Vertigo (1958).
Henri-Georges Clouzot was convinced that Simone Signoret was playing the character incorrectly because she, the actress, knew the ending of the movie and, thus, was giving away too much to the audience with her characterization. One day on the set, Clouzot said angrily, "I should have never let you read the end of the script!"
Simone Signoret hadn't read her contract closely before signing it and didn't realize she was to be paid for only eight weeks, regardless. After sixteen weeks and a wrap, she found out Henri-Georges Clouzot was only going to pay her for the contractually obligated eight. She protested but the outcome didn't change. By the end of the shoot, according to Signoret, she, Véra Clouzot and Henri were no longer on speaking terms. Paul Meurisse and Jean Renoir, who was next door filming _French Cancan (1954)_, were the only ones who made the shoot bearable for her.
Some twelve weeks into the production, Simone Signoret received notice that rehearsals had begun for a stage version of "The Crucible" in which she was starring. She had originally thought there would be no conflict since the shoot was only supposed to go eight weeks and wrap a solid month before The Crucible rehearsals started. Henri-Georges Clouzot would not rearrange the shooting schedule to accommodate her and she had to go straight from the set to rehearsals for the play, get a few hours of sleep in between (maybe) and start over again.
Véra Clouzot went up and down in spirits and when Henri-Georges Clouzot and Simone Signoret would begin to fight, she would "arbitrate or pour oil on troubled waters, depending on the state she was in." The three of them, not unnoticed by observers on the set, mirrored the three characters of the movie, with Henri-Georges Clouzot standing in for Michel.
The message during the credits at the end was one of the first examples of an "anti-spoiler message", requesting the audience not to disclose the plot. In fact, one of the posters for the movie said "See it...beamazed by it.. but......be quiet about it!"
Filming took a lot longer than expected. The shoot was originally scheduled for eight weeks but ran for sixteen. This caused tensions between Henri-Georges Clouzot and Simone Signoret to increasingly mount. "I knew that I was letting myself in for a hell of a time," Signoret said, "[but] I had no idea that it was going to be as wretched as it was for sixteen weeks."