Such were the budgetary constraints on this 25-day shoot, no customary lighting setups were used for the only camera that was hand-held for takes lasting up to 15 minutes. Rehearsals were excluded and, to the relief of the actors, no post-production looping requested.
This is the second time Jared has lost weight for a role the first being Requiem for a Dream (2000). There was only one film where he actually gained weight which was in _'Chapter 27 (2007)' when he played Mark David Chapman the killer of John Lennon.
After playing an LGBT character in this film, Jared Leto then went on to play the Joker in Suicide Squad (2016). The same thing happened to Heath Ledger, who played an LGBT character in Brokeback Mountain (2005) then later played the Joker in The Dark Knight (2008).
Matthew McConaughey's character calls Jennifer Garner's character Nurse Ratchet as he's leaving her office. Obviously this is not her name but it is the name of the nurse from One Flew Over the Cuckoo's Nest (1975) starring Jack Nicholson.
During the scene with the hookers in the beginning, Matthew McConaughey calls the girls "Miss Alaska and Miss Louisiana". McConaughey starred in the series "True Detective", that was set in Louisiana and his character spent many years living in Alaska.