Robert Wise said he was willing to cast a black actor as the lead character (as it was originally written), but since there were no African-American leading actors in Hollywood at the time, he was obligated to switch the character to a white man.
Robert Ryan was a boxing champion while a student at Dartmouth college.
Based upon a narrative poem published in 1928 by Joseph Moncure March, who gave up his job as the first managing editor of "The New Yorker" to devote himself to writing. On the strength of it, he went to Hollywood as a screenwriter, remaining there for a dozen years. In 1948 he volunteered to work on this film, but was turned down. He was incensed that his black boxer Pansy Jones was changed into the white Stoker Thompson.
The clock on the square at the beginning shows 9:05PM, and the same clock at the end shows 10:16PM. The movie takes place in real time.
The shoot took twenty days.