The clock on the square at the beginning shows 9:05 PM, and the same clock at the end shows 10:16 PM. The movie takes place in real time.
While he was a student at Dartmouth University, star Robert Ryan was an undefeated boxing champion. Former boxing professional John Indrisano was enlisted to choreograph the match, blow by blow, and is credited onscreen for "fighting sequences," coaching Ryan for the production. Hal Fieberling, who plays "Tiger Nelson" in the picture, was also an expert boxer, according to LAT.
Martin Scorsese is a big fan of the film and was so impressed by the boxing sequences that he had to deliberately avoid copying any of Robert Wise's camera tricks when it came his turn to make a boxing movie, Raging Bull (1980).
One of the first films to be shot using the device of real time (i.e., the film lasts the same length as the events it depicts). Other notable examples of this narrative device include Rope (1948), High Noon (1952), and Nick of Time (1995).
One of two boxing movies released in 1949 which are now considered seminal examples of the genre - the other film being Mark Robson's Champion (1949).