What If... Ultron Won? - S1-E8
Plot hole: Ultron cuts through Thanos like butter and acquires the Infinity Stones. He does so after he kills all life on the planet (-2). So Thanos has all the Stones (except Vision/Ultron's) years earlier than normal continuity, for no reason. Not just that; Ultron proceeds then to 'silence' the rest of the universe one planet at a time (which would take forever; Thanos wanted the gems exactly to avoid doing that and make genocide efficient). Amongst those planets, one where he fights The Guardians of the Galaxy, including...Gamora, who should be dead or Thanos could have never got the Soul gem.