Only one scene in the entire film--a long shot of the Curies on honeymoon--was actually filmed outside of the studio, and even that was second unit.
As a proper English lady, Greer Garson insisted on having tea served on the movie set every day at 4 o'clock. Once, while filming a scene, the actors were interrupted by a sharp whistling sound. Director Mervyn LeRoy shouted, "Cut! What the hell is that noise?" A voice responded from offstage, "It's Miss Garson's tea kettle, sir!"
In her final years at MGM, Joan Crawford was handed weak scripts in the hopes that she would break her contract. Two films she hungered to appear in were Prisonniers du passé (1942) and Madame Curie (1943). Both films went to bright new star Greer Garson instead, and Crawford left the studio soon after.
Originally planned for Greta Garbo and Spencer Tracy to star in. However, Ève Curie, who wrote the memoir of her mother on which the film was based, thought Garbo was "too glamorous." Her contract gave her star approval, and she used it to insist that Greer Garson be cast.
The third of Greer Garson's run of five consecutive Oscar nominations for Best Actress. She had been nominated for Les oubliés (1941) and won for Madame Miniver (1942). She would be nominated again the next two years for Madame Parkington (1944) and La Vallée du jugement (1945).