Avengers: Endgame theory changes Marvel's best movie

The time travel in Avengers: Endgame never really made sense, but as our heroes journeyed into the past to recover the Infinity Stones, they still did their best to avoid changing the events of the past — with one big exception.

Well, to be fair, there were multiple exceptions (Marvel’s making an entire show called Loki about one of them), but there’s one way the Avengers changed the past in Endgame that never really got enough attention. And a closer look reveals that it could essentially cancel out our favorite entry in the Marvel Cinematic Universe.

Hail Hydra — After the Endgame version of Captain America gets the Mind Stone in the MCU’s 2012, he winds up in an elevator with none other than Brock Rumlow (the HYDRA agent played by Frank Grillo who was still masquerading as a S.H.I.E.L.D. operative at that time). Cap knows Rumlow’s secret. So to get out of the situation without a fight he simply leans over and whispers two words: “Hail HYDRA.”

It’s one of Endgame’s best moments, for multiple reasons. First, it’s a genius twist that shows Captain America’s ability to get out of a tough spot without his fists. Second, it’s a clever Easter egg reference to the comics, where Cap was actually revealed to be a HYDRA agent in a bizarre twist. And third, it’s a direct nod to arguably the best scene from arguably the best Marvel movie: the elevator fight scene in Captain America: The Winter Soldier.

But what if that one moment actually undoes The Winter Soldier entirely?

The theory — TikTok user @bella_billnye points out that the events of Endgame send the Marvel Cinematic Universe on a bizarre new trajectory. If Rumlow thinks Captain America is also in HYDRA, it’s probably only a matter of time before he returns the favor and says “Hail HYDRA” to a non-Endgame version of Cap the next time they're in an elevator together, right?

This would tip Steve Rogers off (since he encountered HYDRA back in World War II) and blow the evil organization’s cover way earlier than intended. That means The Winter Soldier wouldn’t happen, at least not in the way we remember it. Bucky Barnes might not even show up, which would throw off the entire MCU timeline. We might not even get The Falcon and the Winter Soldier.

Maybe Rumlow didn’t have a chance to blow his cover before the events of Winter Soldier. Or maybe there’s an alternate timeline where that’s exactly what happened. Either way, it’s a pretty fun plot hole to think about.

But that’s the problem with the time travel in Avengers: Endgame — the more you think about it, the less sense it makes. The movie gets away with this thanks to one funny scene featuring a Professor Hulk rant, but two years later, fans are still poking holes in Marvel’s script.