User blog comment:PerhapsTheOtherOne/Speculative Spitballing: Goliath/@comment-173.58.100.7-20150608180157/@comment-24891101-20150608200845

Well yes, the Haradrim did bring mûmakil to the Battle of the Pelennor Fields, but the competition between Legolas and Gimli only occurred at the Battle of the Hornburg. It's nowhere mentioned that they continue the game. It's purely an invention of the fans who made the film, and thus not in any way canonical.