Tim Blake Nelson wrote the screenplay with Edward Norton in mind to play the roles of the twin main characters, saying "there would have been no second choice" if Norton had said no.
Edward Norton was so desperate to star in this movie that he took a pay cut, stating in an interview that he "actually got paid half what I usually make".
When Bill asks the rabbi what this all means. She responds that we need to "repair the world." This is a direct translation of the Hebrew term Tikkun Olam which is a central concept of Judaism, to do what can be done to repair or fix the world.
Brady's TVZ tattoo is a reference to musician Townes Van Zandt.