Well, I think it's been implied that Loki escaping with the Tesseract created an alternate timeline, which will lead into the Disney+ series.(1) THE TIME HEIST
Quote Originally Posted by CBR
When Hulk meets the Ancient One in 2012's Battle of New York, the plan shifts a bit, which results in the Avengers borrowing the Infinity Stones on the condition they return them to their timelines at the same moment they were taken. This is the only way to leave the timestream unaffected and not create alternate realities.
However, on multiple missions, people constantly break the rules and tinker with the past. In 2012, Steve Rogers fights himself right after Loki escapes with the Tesseract, not to mention he changes Hydra's actions in Avengers: Age of Ultron when he pretends to be one of them. Steve also chooses to remain in the past with Peggy Carter in the finale, which affects how the Avengers initiative kicked off, as well as the wars they fought after. This ripple would have affected everything downstream, including the snap.
As far as Steve staying in the past, you either believe that he stayed in the past and lived out an alternate reality or he stayed in the past with Peggy like he was always destined to do. I choose the latter, although him showing up with the shield for Sam indicates the former.
Nebula knows that Thanos sacrificed Gamora for the soul stone. She states as much in Infinity War when she talks about Thanos returning from Vormir without Gamora but with the soul stone.(2) THE VORMIR SACRIFICE
Just before the Avengers go on their temporal mission, they divide into teams and do a breakdown of where to find all the Infinity Stones. They detail how to extract them, because they know they shouldn't do anything to alter the timestream. Yet, when they get to Vormir, Hawkeye and Black Widow somehow don't know they need a sacrifice for the Soul Stone.
It's a pretty dumb moment because Nebula knew Thanos killed Gamora to obtain it in Infinity War, so she should have given the duo a heads up. It appears Nebula forgot to tell them for the sake of plot convenience, all so the Avengers could dramatically duke it out to see who draws the short straw.
But why tell Natasha or Clint? It would create unnecessary conflict between the two and jeopardize their mission. She knew one of them would have to be sacrificed, especially since they were the only team in which there was actual love between them (platonic love, but love nonetheless). Better send them to Vormir with as little knowledge as possible and let them figure it out there than have them fight about it or other people try to take their place and fail.
I assume that they took present Nebula's GPS and somehow incorporated it into their ship.(3) TEAM THANOS' TRIP TO THE FUTURE
The first plot hole here revolves around evil Nebula infiltrating the Avengers in the present. When the Avengers snap the "dusted" back to life, evil Nebula uses the time machine to open a portal allowing Thanos' legion to come to the future. However, the quantum tunnel Tony Stark created doesn't work like that: He made it clear the only objects they could pull from the timestream must have the mysterious wrist devices, which are basically temporal GPS locators or tags for his time machine to pull.
Either an alternate reality is created in which Thanos doesn't return to 2014 and complete the first snap, or Tony snaps them all back to 2014. Given that they dusted, it would lead me to believe in the alternate reality theory.The second plot hole arises in the finale, when Tony uses his tech gauntlet to snap Thanos' army away. Killing them here means they don't exist in the 2014 timeline anymore, thus nullifying everything from Guardians of the Galaxy onwards. Once more, without Thanos and his forces there, history's changed drastically and the snap wouldn't ever happen. The main timeline is further affected when Gamora is also taken from 2014 and doesn't return to her timeline.
Again, either an alternate reality is created or Tony snapped them all back to 2014. Given that present Nebula doesn't fade away it would lead me to believe an alternate reality was created.(4) NEBULA'S PARADOXICAL DEATH
When evil Nebula tries to steal the Stark Gauntlet for the Mad Titan, she's confronted by the redeemed Nebula and Gamora in the present. However, in a very emotional standoff, the good Nebula shoots her past self in the chest, killing her.
It's a basic time travel rule being broken here, because by killing her past self, future Nebula shouldn't exist. Yet, once again for plot convenience, future Nebula's alive and well and goes on to help take down the
rest of Thanos' troops. Also, killing Nebula from 2014 affects everything that leads to the snap, thus adding to the series of paradoxes, wherein the very thing Endgame is based on wouldn't happen at all.
I'm really not trying to sound like a jerk here but I've seen the movie three times and absolutely nowhere do I recall anyone saying that the nano gauntlet would only work for Avengers. If that were the case there wouldn't be a need to quickly get the gauntlet away from Thanos and the Black Order when they arrive. Further, the gauntlet clearly morphs to fit Hulk's hand so one would conclude it could do the same for Thanos.(5) THANOS USING THE STARK GAUNTLET
In the finale, after winning a brawl with Captain Marvel, Thanos puts on the Stark Gauntlet, but the Russo brothers apparently forgot the rules they created for this. This gauntlet isn't designed to fit the Mad Titan, it's nanotech is programmed to fit Avengers only. That's why the Hulk wields it to snap the deceased back to life and also why Tony dons it to snap away Thanos' forces. Thanos shouldn't be able to force his hand into it or else it'd break
We don't know what Thanos feels when he wears the gauntlet with full stones. We know the Hulk and Tony feel pain but Thanos is much stronger than them. But we know Thanos didn't realize they were missing because THANOS DIDN'T REALIZE THEY WERE MISSING!Another plot hole arises when Thanos wears it and snaps his fingers, not realizing the stones are missing. Upon rewatching the scene, Thanos looks at the gauntlet before he snaps, so he should have seen the stones absent. More importantly, his mind and body are connected to them, so once Stark took them back, the Mad Titan should have felt the link being severed and knew he couldn't perform another snap.
And no, he never looks at the side of the gauntlet with the stones. Again, I've seen the movie 3 times and that never happens.
I don't think it's a plot hole if you really think about it. As others have said, Tony just creates amazing things all of the time with no effort.
In Iron Man he created his armor using basically nothing. In AoU he created AI (albeit by accident and via the use of an infinity stone). And in Infinity War he had created that nano-suit armor off screen which basically does anything you could possibly want.
He's not. Rocket even specifically says that he isn't the only genius in the galaxy.
Zac Efron should play Nova.
In "Ant-Man", Henry Pym did say something about how his shrinking technology could truly change the world while Stark's armor is comparatively a toy. But IM3 showed that even when something is outside his area of expertise and he's drunk and isn't even interested, he can come close to a breakthrough that the world's leading expert on the subject can't do. When he puts his mind to it, he can accomplish in days what the alleged top expert took years to do. So the time travel was sort of a stretch but not inconsistent with established continuity.
But the first Iron-Man movie led off the MCU and was a phenomenal success and a huge amount of that was RDJ. There are those who say he wasn't just part of the IM movies but that he almost was the IM movies. He certainly remained the most popular character so I can understand why they have largely built the team movies with him as a bit more the main character that anyone else.
Power with Girl is better.