One Mind Blowing Secret From Every MCU Movie
16. Why Banner's Transformation Took Place Off Screen - Avengers: Endgame
One of the most jarring moments of Avengers: Endgame came when Scott Lang (Paul Rudd), Natasha Romanoff, and Steve Rogers went to speak to Bruce Banner, revealing that the latter had managed to merge both halves of his personality off-screen. This was a huge development that felt like it deserved some more attention.
However, that is how it was always supposed to be. As revealed on the Endgame director's commentary, after their issues throughout Infinity War, Banner and Hulk would have burst forth from the Hulkbuster armour in Wakanda as Smart Hulk, and kicked Cull Obsidian's sizeable arse.
It was only decided in post-production that the moment didn't work. The Russo brothers didn't like the idea of Banner getting a win like this in the middle of a succession of losses in Infinity War's third act. It took away from the devastation of the Avengers' defeat, so they decided to get rid of the development and instead keep Banner as just Banner with a few last-minute CGI changes.
The issue with this is that at the time of Infinity War's editing, Avengers: Endgame had already been shot, leaving the biggest breakthrough in Banner's life since becoming the Hulk to sit off-screen with other massive MCU events, like Thanos' destruction of Xandar, or Natasha's defection to S.H.I.E.L.D.