Nicole Kidman performs the intro-song, a cover of "Dream a Little Dream of Me". It was director Susanne Bier's idea to have her perform it, and Kidman's husband Keith Urban helped her record the cover.
Actor Michael Devine, who plays Detective Paul O'Rourke, was a real-life Detective Sergeant in the NYPD.
The locker room scene was shot without rehearsals, as director Susanne Bier likes to do, and Nicole Kidman was not even warned that she would be facing Matilda De Angelis in full nude, which wasn't in the screenplay: "Full nudity was not foreseen, but it was functional to the scene. If the woman in front of you is completely naked, an inch from your face, then you perceive her as threatening," De Angelis explained.
Donald Sutherland plays Nicole Kidman's father for the second time. The first time he played her father was in "Cold Mountain" (2003).
Based on: You Should Have Known, by Jean Hanff Korelitz.