Mushy Callahan was the junior welterweight boxing champion during the late 1920s. He joined the film industry as a prop man and grip for Warner Brothers in 1934. He then was promoted to boxing instructor for studio stars and helped stage the fights for films such as Kid Galahad, Gentle Jim, and Rebel Without a Cause. He was helping James Dean train for his upcoming film Somebody Up There Likes Me when Dean died. Callahan also helped stage the ballet movements for a musical number in Oklahoma. Just before retiring, he trained James Earl Jones for The Great White Hope. The former fighter has also had small parts in several films, including Madison Square Garden, and Hello Dolly!