Director Justin Kurzel told Lucas Pittaway not to talk much to any of the actors on set, to help the emotional state of his character.
There was a subplot based on actual events, which revealed Robert and Barry as lovers in the past. It was cut, but it can be found on the DVD deleted scenes.
Daniel Henshall (John) lived in the Snowtown area for 6 weeks in a hotel, and got to know the locals to help develop his character.
The game the brothers are heard to be playing at the beginning on the movie is 'Alex Kidd'. The console version is Sega Megadrive.
The number Jaime dials on the phone is 000, also known as Triple Zero, and is the primary emergency number in Australia.