Keira Knightley does all of her own singing in the film. She worked with vocal coach Claire Underwood to prepare for the film.
Producer Rebekah Gilbertson is the granddaughter of the real people played by Keira Knightley and Cillian Murphy in the film.
Sharman Macdonald wrote the role of Caitlin with Keira Knightley in mind, but Keira chose to play Vera instead.
The film's title is subtly shown, in part, throughout the film in various places. Most noticeably after we see Caitlin's affair it appears as a silhouette on the curtain.