* CastTheExpert: Richard Farrell, who plays one of the HBO camera men, is actually a director and news camera man himself. So he's essentially playing himself.
* DevelopmentHell: A sequel chronicling the legendary Ward-Gatti trilogy that was the highlight of both Boxers careers (and indeed, considered one of the best trilogies in the history of the sport) has been in development since 2012, with Jerry Ferrara being cast as Gatti, but no further development has come out since and the project seems dead on its tracks.
* DisownedAdaptation:
** The real Dicky Eklund hated the portrayal of his mother and sisters in the film, with one of the sisters walking out of a screening in protest.
** According to Creator/AmyAdams, the real Charlene disliked the skimpy outfits she wore - as she did not dress that way in real life. She also didn't like being depicted as getting into a CatFight.
** The real Micky on the other hand gave Creator/MarkWahlberg the ApprovalOfGod.
* DoingItForTheArt: Both Creator/MarkWahlberg and Creator/ChristianBale worked for lower rates than usual, with Wahlberg in particular waiving his own salary and taking no upfront fee for the film.
* DyeingForYourArt:
** Creator/ChristianBale lost thirty pounds to play the crack addicted Dicky.
** Creator/MarkWahlberg trained for four years to be ready when the film eventually got made.
* FakeAmerican: Creator/ChristianBale as Dicky.
* InvisibleAdvertising: Creator/MelissaLeo was receiving Oscar buzz for her performance in this film but the studio didn't put much effort into campaigning for her. Frustrated at this, Leo put out her own ads in trade publications to persuade AMPAS voters to pick her.
* MethodActing: In true Christian Bale tradition, he stayed in character even when the cameras weren't running. This extended to Melissa Leo too.
* NoStuntDouble: To amplify the film's realism, Creator/MarkWahlberg refused a stunt double and took real punches during the fight scenes. This resulted in him nearly getting his nose broken a couple of times.
* PlayingAgainstType: Creator/AmyAdams is known for playing [[NiceGirl sweet-natured]], [[ManicPixieDreamGirl playful]], and [[RuleOfGlamorous at times quite glamorous]] heroines. Cue ''this'' film, where she's suddenly playing a tough broad who's filled with sass and not afraid to get into brawls herself. Creator/DavidORussell himself indicated that this was his whole intent behind casting Amy: to show her as most definitely [[Film/{{Enchanted}} "NOT a princess"]].
* RealLifeRelative:
** The man who rushes into the bar to say that Dicky is getting attacked by the police is Sean Eckland, Dicky's nephew in real life.
** A cop who jokingly arrests the real Dicky at the end is played by the son of the officer who originally arrested him in real life.
* TroubledProduction: Amazingly averted. This only bears mention due to Creator/ChristianBale's bad temper and David O. Russell's infamous anger issues and attempts at violence.
* WhatCouldHaveBeen:
** Creator/DarrenAronofsky was originally attached to direct. He did remain on the film, serving as an executive producer. In a curious twist, Creator/DavidORussell wound up nominated for Best Director against Aronofsky (nominated for ''Film/BlackSwan'') at the 2011 UsefulNotes/{{Academy Award}}s.
** Creator/MattDamon and Creator/BradPitt were previously attached to play Dicky Eklund. Creator/MarkWahlberg talked to Eminem about taking the role, but Music/{{Eminem}} ultimately declined to work more on his music.
** Wahlberg sent the script to Creator/MartinScorsese, hoping he would direct, but Scorsese turned it down.
** Creator/MichaelFassbender auditioned for a role.
** Creator/EmilyBlunt turned down a role.
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