Daredevil actor Viggo Mortensen angered director Ed Harris on the set of new movie APPALOOSA, by challenging a stuntman to a dangerous horseriding race. After perfecting his equestrian skills on the set of movie Hidalgo, Mortensen dared a co-star to a race while standing on the horses' saddles - and invited cast and crewmembers to bet on the outcome. The Danish actor's saddle slipped and he fell to the ground at high speed. He was unhurt, but Harris was furious his star risked his health, and yelled, "What the hell do you think you're doing?" reports the National Enquirer. Mortensen was banned from riding horses for the remainder of the shoot.