Mitchell admitted that his desire to take on the heavy subject matter--the death of a child--was "a personal need to purge some feelings" (he lost a brother) and also because "I'd like to do it because I've never done it." While that excuse works for actors (he was one for some time), he is surprised when directors are met with resistance like 'but you've never done anything like that before, why would you want to do it now?'
For example, Dianne Wiest as Kidman's mother had an emotional scene which they decided to shoot in the basement rather than the garage, even though that's where it looked better, because the noise from LaGuardia airport was too distracting. In another emotional scene, in which Teller and Kidman are sitting outside at a park bench, they ran their Red camera continuously, going through the scene over and over again without stopping until they got each line without the noise of the planes that were taking off every forty seconds.
"There was no other reason to be there than for the subject matter and reverence for the film," said Eckhart. Thus everyone involved was fully committed. "It was an actor's dream…working with a Pulitzer-Prize winning play, with John, Nicole…everyone comes to play and be the best they can be. And in this market it's tough to make these films. It was one of those movies in your career you couldn't pass up. Nicole is a great actor, and I wanted to take that journey with her."
Eckhart came to the project pretty late, and did not see or read the play beforehand, he said: "All I had to do was think about my son who has died." His work as an actor was to "imagine your child is dead and you feel responsibility and guilt." He admitted: "It seems like an uncomfortable place to be, but it's a wonderful place to be as an actor."
The play and screenplay were written by David Lindsay-Abaire, and Mitchell considers the screenplay to be even better than the play, he said: "It feels wider, bigger," mostly because it takes the story outside of the couples' home, where the entire play resides. There are many scenes, and even characters, that appear in the film but were not in the play.
Mitchell recalled other films that dealt with this subject matter - Lars von Trier's Antichrist, for example (which he does credit for being incredible filmmaking). But he finds that they rarely, if ever, "add" to someone's understanding. He believes that if a piece of art deals with a heavy subject matter, it ideally should contribute to someone's ability to deal with - not just reinforce - the misery of the situation. "Hopefully this [film] is a set of tools in learning how to deal with this," he said, hoping that none of us experience the loss of a child but recognizing that we all inevitably deal with death. "That's what art is for," he said, "you watch someone else going through it and you're able to purge it by proxy. Art can cleanse you by going through the rabbit hole and coming back to the light."