The scene where Brit Marling leaves prison was achieved by getting Marling to pose as a yoga instructor and enter and leave the prison for real.
Brit Marling wanted William Mapother because she had been haunted by his performance in In the Bedroom (2001). Mapother agreed to make the film for $100 a day.
Filmed in and around New Haven, Connecticut - Mike Cahill's hometown. Cahill knew that by filming there he would be able to call on favors from family and friends, helping keep costs down. This is particularly true of the car crash that is an integral part of the film. One of Cahill's friends is a police officer who was able to shut down some roads to allow for filming.
The film came about out of conversations between Brit Marling and Mike Cahill about what it might be like to meet yourself.