Dalton Trumbo was a contributing writer, but left because his interpretation of the novel differed from producer Preston Sturges. Sturges also left the production (and declined onscreen credit) because of artistic differences with director René Clair
Veronica Lake and Fredric March did not like one another, due in part to some disparaging remarks March made about her. During filming, Lake delighted in playing pranks on March, such as hiding a 40-pound weight under her costume when March had to carry her in his arms. In another scene in which the two were photographed only from the waist up, Lake stuck her foot in March's groin.
Veronica Lake was best known for her iconic hair style of having her right eye covered. Many women copied the style which caused problems since they were working in war plants and their hair kept getting caught in the machinery. Lake was asked to change her style until after the war. When she did she lost her iconic look and her popularity soon faded along with her career.
Joel McCrea was initially cast as the lead, but declined the role because he didn't want to work again with Veronica Lake, his co-star in Sullivan's Travels.
Many scenes had to be reshot because of the unprofessional behavior of Veronica Lake. Fredric March, her co-star, found her annoying and started to call the movie "I Married a Bitch". Other Lake co-stars held her in the same low esteem.
One of several Paramount Pictures productions purchased by United Artists for theatrical release in 1942-1943 during a product surplus of the former company, and a product shortage of the latter.
Several cast members listed in studio records did not appear in the movie. These were (with their character names): Reed Hadley (Young Man), Jan Buckingham (Young Woman), Florence Gill (Woman Playing Chess) and Walter Soderling (Man Playing Chess).
Sol Sacks, creator of Bewitched, stated in an interview for "True Hollywood Story: Bewitched" that he drew inspiration both from "I Married a Witch" and "Bell, Book and Candle" (1958) in creating the iconic TV series. Columbia Pictures owned the rights to both of those movies. As it also owned the television studio that was to produce "Bewitched," Sacks didn't worry about getting sued.