Christina Hendricks was cast alongside Naomi Watts and Liev Schreiber back in 2011 when the project was announced. Hendricks dropped out while the film was stuck in development and eventually Elisabeth Moss replaced her.
James Brown sang in the ring before the Ali-Wepner fight and did a pre-fight performance on screen in Rocky IV.
Liev Schreiber & Naomi Watts were a couple in real life, until they called off their engagement in 2016.
Chuck Wepner was the real-life inspiration for Sylvester Stallone's character Rocky Balboa.
Was originally called "The Bleeder", but changed to "Chuck" due to viewers thinking it was a horror film, as well as other movies with the same name according to Chuck Wepner. In several European countries, the movie was still released as "The Bleeder", though.
Liev Schreiber and Pooch Hall who play Chuck Wepner and Muhammad Ali in the film, have also starred together as half brothers in the Showtime original series Ray Donovan.
Chuck tells Linda the bartender that she takes a good license photo, but New Jersey didn't start putting photos on licenses until the late 1990s.
Chuck states, "What Bayonne makes, the world takes". This is in reference to the quote on the Lower Trenton Bridge in Trenton, NJ, "What Trenton makes, the world takes". This refers to the manufacturing industries that dominated Trenton in the early 1900's.
Chuck gets into a phone booth on the street next to a No Turn on Red sign. Being able to turn right on red wasn't law in NJ until 1979.
Liev Schreiber, unlike his character Chuck Wepner, does have a role in the "Rocky" franchise. He assumes his real-life role as the narrator of HBO Sports Documentaries in the film "Creed", a spin-off of Rocky's saga.
Liev Schreiber has acted in two different boxing movies set in New Jersey, this movie and The Hurricane (1999)