Many of the murder scenes were shot in the locations where the real-life murders took place.
To make sure Johnny Depp's performance was true to the real James "Whitey" Bulger, Scott Cooper hired some of Bulger's old associates as consultants to the film. Each of them praised Depp's performance, saying, "That's Whitey."
James 'Whitey' Bulger was killed October 30th, 2018, at United States Penitentiary Hazelton, near Bruceton, WV. Bulger was in a wheelchair, and had been there less than a day. He was beaten to death by multiple inmates armed with a sock-wrapped padlock and a shiv.
In an interview on Jimmy Kimmel Live! (2003), Johnny Depp admitted that he broke his rule of not watching his own movies with this one. He was at the film's debut in Venice. He was about to skip out of watching the film, but director Scott Cooper asked him to stay, so he did.