After Producer David O. Selznick fired Cinematographer Harry Stradling Sr. and hired Gregg Toland to take over the photography of this, the remake of Intermezzo (1936), he asked Toland how it was possible that Ingrid Bergman looked so beautiful in the original European production and so ghastly in his Hollywood version. Toland replied, "In Sweden they don't make her wear all that makeup." Selznick immediately ordered retakes with the natural look which so dazzled the world a year later when he loaned her out to Warner Bros. for Casablanca (1942).
Leslie Howard had only a rudimentary understanding of the violin. During closeups, he kept his hands by his side as violinists bowed and fingered the board. This same trick was performed by Isaac Stern for John Garfield a few years later in Humoresque (1946). Ingrid Bergman did have some knowledge of piano, and her fingering is correct. The music was provided by others for both: Toscha Seidel for Howard and Norma Drury for Bergman.
David O. Selznick bribed Leslie Howard into accepting the role of Ashley in Autant en emporte le vent (1939) by giving him the right to co-produce this film.
In this, her first American film, and also in her last feature film, Sonate d'automne (1978), Ingrid Bergman plays a concert pianist.