Robert Pattinson stated, that after Twilight ended he knew he had to play these kind of roles to avoid getting typecasted, and that he wanted the role so much, that in the days leading up to the audition, he even dreamt of his character Rey. When he was at David Michôd's house for the audition, he couldn't start to actually play the character for 45 minutes because he had so much anxiety.
The scene which involves Rey (Robert Pattinson) listening and singing along to the song "Pretty Girl Rock" by Keri Hilson, was put there by the director to remind people that in a normal, civilized world, Rey would still be a kid listening to pop songs and swarm for girls.
The film was originally going to be written by both David Michôd and Joel Edgerton for Edgerton's brother, Nash, to direct it.
Director David Michôd asked Robert Pattinson to watch the documentary "Bully" (2011) to better understand and prepare for the character Rey.