At Mary Astor's suggestion, her hair was cut into the chignon shape she wears in the film because rolling and styling it took too long. She then wore it the same but a bit longer in The Maltese Falcon (1941), causing a fashion craze.
When Pete returns from seeing his lawyer, early in the film, he finds Sandra's agent in the living room listening to her latest recording. This is an excerpt from the first movement of the Piano Concerto No 4 in D minor by Anton Rubinstein, a great rarity and certainly not recorded by anyone else in 1941. It was possibly chosen by Max Steiner because it was no longer in copyright, but whatever the reason, it was a most unusual and sophisticated choice.
Mary Astor mimed playing the piano in this film extremely convincingly, being an accomplished pianist in her own right. However, the actual piano playing on the soundtrack was dubbed by Max Rabinowitz. When close-up shots were required, Norma Drury 's hands are those we see on the piano.