12 Biggest Retcons In The Marvel Cinematic Universe
11. Vision's Drastically Reduced Powers
When he was created in Avengers: Age Of Ultron from the sub-titular psycho robot's replacement body, the Mind Stone and the remnants of J.A.R.V.I.S.' A.I. (it's a convoluted movie, OK?), Vision was already a pretty out there being for the MCU. And that's before you get to his powers, which included flying, phasing, invulnerability, super strength and the ability to shut down Wi-Fi connections.
However, because his powers were so metaphysical and even more poorly defined, this made the character more than a little OP'd, something that would prove an issue in a more grounded movie, such as Captain America: Civil War. And so the Russos changed him.
Not only does he spend most of the film sporting a fetching shirt/jumper combo, but he also displays a vastly reduced power set. He can be halted by a pair of sonic arrows (from career Weakest Avenger Hawkeye, no less) and in the show-stopping airport scene seems rather ineffectual against a bunch of relatively barely-enhanced humans, firing the odd laser but otherwise not able to stop Captain America getting to his plane. At the end of the battle this is chalked up to him developing emotions for Wanda, but things were parsed down well before then.
Actually, a similar power decrease is true of Scarlet Witch also, although that one feels like less of a big shift.