Although there was a script reported to be between 400 and 600 pages long, all of the scenes were improvised.
During filming, writer and director Terrence Malick would use a technique he called "torpedoing", where he would unexpectedly send people into the scene to get a reaction from the actors and actresses who were performing.
Christian Bale had no lines to learn and writer and director Terrence Malick only gave him the character description.
According to Christian Bale, Terrence Malick didn't tell the actors and actresses what the movie was about.