Dwayne Johnson is getting the full MMA experience during the filming of his upcoming movie, “The Smashing Machine,” as he became injured when filming a scene. Johnson, aka The Rock, stars as former two-time UFC heavyweight tournament champion Mark Kerr in the film and has been on the training mats for months in preparation for the role. Like a vast majority of MMA fighters who experience setbacks or even fight cancellations due to injuries, Johnson now has that first-hand experience as well, as he showed off huge swelling in his right elbow.