The Elder’s initial refusal to train Strange
This feels like a low blow for Strange doctor, but since the MCU is a complete job, I must point out that it is a strange mistake that the Ancient One refused to train Stephen Strange right away. This is thanks to Avengers Endgame, where the Hulk visits The Ancient One long before he officially meets Strange. However, because time is relative, she knows who Strange is and decides to give the Hulk the Time Stone because Doctor Strange “is the greatest” of them. I know Doctor Strange came years before this moment in real life, but considering how carefully designed the MCU is, someone should have remembered it.