In the opening credits of the U.S. prints of this movie, available on DVD, the title appears in the plural: "Challenge of the Gladiators".
Peter Lupus shaved his chest for this movie, giving his torso the smooth, oily, suntanned look popularized by Steve Reeves in his "Hercules" roles. (Lupus's naturally-hairy chest can be seen on display in his centerfold photos in the August 1974 issue of 'Playgirl' magazine.)