Easter Egg: As per usual in one of Chris' films, if you look closely, you should notice an odd blue book called "Nosey" at some point randomly placed amongst the mise-en-scene. This is common in all of his films bar Unbidden (2013) where they simply forgot to add it into frame.
The last scene with the phone call conversation was added in during the last few days of post-production as a simple way to get the ending finished since the last bits of dialogue were never filmed on-location due to time restraints. In fact, SPOILERS: when it's the over-the-shoulder shot of Boss, it is in fact the actor, Jack Dixon-Roxburgh covering for Dylan Nicholson (who played Boss throughout the rest of the film). Dylan just recorded his lines separately and sent them to the editor later on.