Avengers: Infinity War - 13 Previous MCU Scenes It Completely Changed

3. Thor's Powers - Thor: Ragnarok

In Thor: Ragnarok, one of the key narrative concerns was Thor's unspoken search for "worthiness." He might have been able to wield Mjolnir, but his status had become defined by the weapon, rather than by himself and when it was removed by Hela's destruction of Mjolnir, he suffered a crisis.

He was shorn of his hair as further exaggeration of the Samson allegory and rendered mostly powerless. But then, of course, he realised that the Special Stuff was in him all along, thanks to a vision of his father, and that his powers could be summoned without Mjolnir, which changed the game entirely and made him even more powerful.

But then, because that would be way too devastating to Thanos' own terrifying power, the Russos undid all of that in Infinity War and made it so that Thor once more needed a weapon. That's basically the quickest retcon in MCU history (and there have been a lot of them).