The fight
The fight in this film is considered perhaps the best staged for a Hollywood film. Both Robert Ryan and Hal Fieberling, (Baylor), had experience as boxers. Ryan was an intercollegiate boxing champ at Dartmouth and Fieberling had a 14-8 record as a pro heavyweight.
Their fight is very exciting and the excesses of make-up often employed in Hollywood fights are avoided. But the fight is still too "busy", even if you consider it was a four rounder and that the Ryan character had an extra motivation for "getting the guy". They throw nothing but haymakers and land most of them and just keep milling for every second of every round. It makes Hagler-Hearns look like a walk in the park. In most Hollywood films we see action like this and jump forward to a later round. Here we see the whole thing and they look like those boxers in that arcade.
It takes a little bit away from a film that otherwise leaves nothing to be desired. The most realistic fight in a Hollywood film is probably Rocky I, where the boxers miss punches, get tired, look at the clock, etc. Of course, that was the last Rocky film that had any realism to it.