Paul Bettany and Jennifer Connelly's apartment was in front of a homeless couple that disappeared after Hurricane Sandy. The film is dedicated to them.
Anthony Mackie looked so believable as a homeless person that apparently one day while filming in New York, one of his friends saw him and asked if he needed money.
This is the first film Paul Bettany directed.
Paul Bettany decided to film Jennifer Connelly after his experience with giving a homeless person a $20 bill. The scene, in the beginning, shows Connelly at an angle that would be from her perspective, as opposed to seeing the full frame with people giving her money. This is because Bettany gave a homeless man a $20 bill while walking into a store, received thanks from the man, and walked out to see the man put out his hand again. When Bettany told the man he had just given him $20, the man said, "Oh, that was you," to which Bettany realized a perfect frame would not be the whole picture but rather what is in front of them.
Ron Howard, Darren Aronofsky, Joss Whedon and other people Paul Bettany that has worked with all helped Paul on the directorial process.