Nicole Kidman stated that she got the flu during filming, but powered through and tried to use it in her performance. For the final scene in the movie with her character's daughter, Kidman said she was so sick while filming she could "barely stand."
Sebastian Stan originally auditioned for the role of 'Silas', but director Karyn Kusama told him she felt that he'd be better for the role of 'Chris'.
Nicole Kidman's immersion in her role as 'Erin Bell' took weeks, even months to wear off;"I'd find myself shuffling and I'd ask myself why and oh because Erin's still there."
When Erin Bell (Nicole Kidman) and Chris (Sebastian Stan) are rehearsing their history about how they met , just as Chris says "I like Dire Straits" you can hear "The Man's Too Strong" by Dire Straits This songs talks about murder and robbery so it fits this movie very well.
While preparing for his role, Sebastian Stan met an FBI agent who was on the TV series, "Inside the FBI" in New York who gave him some tips.