At one point - given as 1933 - Jimmy Braddock reports a dream of dining at the Ritz with Mickey Rooney. Then only 13, Mickey Rooney was in the film business but not a name to recognize in Braddock's slum. He starred in a series of comedy shorts at the time, but going by the name of Mickey McGuire. Only from the late 1930s through the 1940s would Mickey Rooney become a top star and household name.
The credits list Benny Goodman's version of "Don't Be That Way" as the song playing in the club when Jimmy Braddock meets Max Baer. That version of the song was first performed/recorded several years later, in 1938, at Carnegie Hall.
When Mae and the kids are stealing wood and see a man leaving his wife, the man walks past a modern style blue USPS postal collection box. In the 1930s the boxes were olive drab colored and were squarer in design.
Jimmy Braddock goes to Central Park in March, 1935 and walks through a Hooverville in search of his friend Mike Wilson. New York's primary Depression Hooverville in 1935 was located on 10th Avenue near the East River (as portrayed in My Man Godfrey). There was a small Hooverville in Central Park located in the drained reservoir, not on the grass as portrayed in the film. When adequate fill could be found for it, the homeless were evicted, and the area was transformed into the park's Great Lawn. Landscaping work was completed by April, 1933, so Central Park's Hooverville had been gone a full two years when Braddock visits it in Cinderella Man.
The receipt that Jimmy Braddock gives at the welfare office is about $50 off from the actual amount that Braddock had borrowed. Russell Crowe pointed this out to the director who decided to 'leave it in to prove that it's just a movie'.
During the press conference before the Max Baer fight, one reporter identifies himself as being from the New York Herald. In fact, the paper had been known as the Herald Tribune since 1924, when the Herald and the Tribune merged.
When Jimmy Braddock first shows his wife the $175 his manager gave him, in order for him to train and get back in shape, he holds the money between his index finger and his middle finger. In the next shot, he holds it between his thumb and his index finger.
In a shot of Joe Gould sitting in his car, you can clearly see the leaves of a palm tree reflected in the automobile's window. This scene takes place in the New York/New Jersey area, where there are no palm trees.
Max Baer is shown wearing a robe with his name on the back. In reality, the robe that Baer wore to both of his title fights was a prop from the movie The Prizefighter and the Lady. Baer played a character named "Steve Morgan", and that was the name on the back of the robe.
When Braddock is viewing the footage of Max Baer killing Frankie Campell in the ring, at the end two people start to pick up Frankie's body. His left arm starts to slide off his body until he raises it slightly for a moment.
The family enters the apartment after the electricity has been turned on again. Jimmy Braddock is the only one with snow covering his hat and jacket. The rest of the family has no snow on their outer clothes.