9. Ebony Maw Actually WAS Around In 2014
Avengers: Endgame obviously changed a lot about the past, since it undid Thanos' Decimation and also ruined lots of the past, even if we're not really allowed to even talk about all of that... But it also did something subtle to Thanos' past that might go slightly unnoticed.
When Thanos learns of the future Nebula on Morag, he has his 2014 version of her shackled and explores her mind to find hints of what the future Avengers' plan is. Because, of course, brain WiFi can be picked up by different versions of the same character from different parts of the timeline.
Anyway, all confusing science aside, the sequence establishes that Thanos' entourage at the time includes not only his daughters, but also Ebony Maw, who made his debut previously in Avengers: Infinity War. In Guardians Of The Galaxy, it was established that Thanos was working with The Other, but it appears that this retcon was designed to make the Maw a longer-serving servant to the Mad Titan and wipe The Other out entirely.