Primo Carnera was the world's heavyweight boxing champion when this film was made and released. He refused to make the movie using the first script, which had him knocked out in the end, but agreed to a revised script with an additional $10,000 salary.
Max Baer was the leading heavyweight contender for the title. Both he and Carnera made their motion picture debuts in this film.
Fred 'Snowflake' Toones is in studio records/casting call lists for the role of "Trainer," but he did not appear or was not identifiable in the movie. A Contemporary Motion Picture Herald article stated that Lionel Barrymore, Jean Hersholt, Lupe Velez and Johnny Weissmuller were to appear as fight fans in the audience of the championship fight, but they were not seen.
Jack Dempsey plays himself in the improbable capacity of a referee in the climactic fight. While giving the fighters instructions, he places unusual emphasis on the rule that requires the standing fighter to go to a neutral corner in the event of a knockdown. This undoubtedly is an allusion to the famed Long Count. In a 1927 title match, Dempsey knocked Gene Tunney down in the seventh round, but failed to go to a neutral corner immediately, which caused the referee to delay the count. Tunney recovered and won the fight.
In an interview, Myrna Loy stated that Max Baer carefully watched Primo Carnera's boxing style during the filming and used this information to beat him in their real-life match for the title in March, 1934.
Max Baer wore the robe from this movie, with his character's name, Steve Morgan, on the back for both of his heavyweight title fights (against Carnera and Braddock).
The movie was banned in Germany because Max Baer was a Jewish boxer.