As an actor Duff first starred in the movies S.W.A.T. and Welcome to the Jungle in 2003. He has also starred in the films Dodgeball: A True Underdog Story, The Eliminator, The Marine, Lords of the Underworld, The Game Plan, Blood: The Last Vampire, Perfect Combination, and Django Unchained. He has also appeared in episodes of the TV series CSI: Crime Scene Investigation, The Game, Two and a Half Men, Revenge, Sons of Anarchy, Workaholics, Scorpion, and Brooklyn Nine-Nine. In 2012 Duff was nominated for a Screen Actors Guild Award for Outstanding Performance by a Stunt Ensemble in a Motion Picture for Transformers: Dark of the Moon. He also did stunts for the 2011 movie Thor.