The creative team was initially worried about casting the 22-year-old Carey Mulligan in the role of a 16-year-old but was convinced by her screentest. Rosamund Pike reportedly really wanted the small part of Helen because "no one ever lets me be funny."
Director Lone Scherfig says she experimented with giving the actors and actresses options during scenes. For instance, she told Peter Sarsgaard that if he felt like it, he could start a conversation with an extra playing a doorman in one scene despite no written dialogue.
Orlando Bloom dropped out a week before filming began. Dominic Cooper, who had previously been in talks, replaced him.
At the beginning of this movie, Jenny's fringe is neatly parted. Once she becomes more and more involved with David, her fringe starts to descend until it is entirely down. This shows she is now a part of his world. Then, as she moves away from him, her hair becomes parted again.
Carey Mulligan mentioned in an interview at the Sundance Film Festival that some of the most enjoyable moments of filming were when some actors and actresses only came in for a day or so, like Sally Hawkins and Dame Emma Thompson, and she particularly enjoyed the four scenes she shot with the latter, whom she described as being "amazing," and called her acting "brilliant"