After retiring from boxing in 1932, Callahan refereed hundreds of matches, and he had a 30-year career in Hollywood, taking small roles in movies, most with boxing themes, as well as working as a stuntman, trainer and boxing adviser on movie sets.
After leaving the sport of boxing in 1932, Callahan worked extensively in the entertainment industry, participating in hundreds of matches as a referee, and having a 30-year career in Hollywood, where he appeared in films that often revolved around his expertise in boxing, including stunts, training, and consulting.