The film was completed according to the director's wishes after his death, but producer Serge Silberman had it reduced from the initial 140-minute version by about 24 minutes to enhance its commercial possibilities. The missing footage remains lost.
Catherine Spaak got her big break when her uncredited brief appearance as Nicole in this film caught the eye of a Paris TV reporter. Sophia Loren happened to see the reporter's interview with Catherine on TV. She immediately thought she looked perfect for the lead role in "I dolci inganni" (Sweet Deceptions, 1960) which was being cast by her producer-husband Carlo Ponti.
According to the 1964 press materials that are included in The Criterion Collection DVD, Jacques Becker first read of the 1947 La Santé Prison escape attempt in a newspaper. Years later, he found out that José Giovanni had fictionalized the same escape attempt in his 1957 novel The Break. Becker contacted Giovanni's publisher, Gallimard, and Becker and Giovanni collaborated on the screenplay of Le Trou.