The CW sci-fi series Supernatural kicked off the final day of Comic-Con with a spectacular presentation. Starting with a clip of show stars Jared Padalecki and Jensen Ackles — as themselves — headed down to Comic-Con the Hall H. They cracked jokes and drove off, but as the screen went black, legendary rock band Kansas of the ’70 and ’80s started blaring the de facto theme song of the series “Carry On My Wayward Son” on the Hall H stage. The crowd erupted with applause as…