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7 ‘Avengers: Endgame’ plot holes that need to be explained, and one huge question [SPOILERS]

Updated Apr 27th, 2019 2:46AM EDT
Avengers: Endgame Plot
Image: Marvel Studios

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There’s no excuse not to see Avengers: Endgame now that it’s in theater. Even if you’ve never seen a single MCU film, and even if you’re not a comic book fan, you should still go. You’ll have an amazing time, and I promise you that you won’t even want to pee for the whole duration of those amazing three hours. Check out our spoiler-free review.

But no matter how well-made the film is, it’s not perfect, and I’m going to address several plot holes that Marvel has to fix. Some of them are minor, but others are more significant. And we can easily speculate on several of them, but we still can’t quite explain them away yet. That said, you should know that several spoilers follow below, so you should avoid this post until after you’ve watched Avengers: Endgame.

I will also remind you not to share spoilers out in the wild, whether you’re talking about the film in public or on social media. This is your last chance to avoid the spoilers below (and a final warning from the cast):

Thanos’s Pym particles

Marvel handled time travel rather well to prevent it from becoming a mainstream tool that can be used to fix past events. We’ve already explained how time travel works in the MCU (read about it here). In short, you need a special GPS, a protective suit, and enough Pym particles to go back in time and return to the present.

Dr. Hank Pym developed the Pym particles many decades ago, well before he even met Scott Lang, who took over the Ant-Man mantle. They’re used to power the whole resizing thing that Ant-Man does, but thanks to Tony Stark’s Quantum Realm time machine, they’re also useful for traveling through time.

We know that each hero had enough Pym particles (either one or two vials per person) for a round trip, which brings us to Thanos’s Pym particles.

When 2014-Nebula comes into the future, she’s using technology she took from 2023-Nebula, which means she has the GPS, the suit, and a Pym particle vial. So how did she pull 2014-Thanos to 2023 without him having the same key components? The most straightforward answer is that Thanos and his smart goons replicated that technology. After all, Stark — and Pym — aren’t the only geniuses in the Marvel Cinematic Universe.

Image source: Marvel Studios

A more advanced alien army can probably replicate that tech. The movie, however, doesn’t make it clear why it’s so easy to bring a full-sized ship through the Quantum Realm, and we don’t have much time to think about it anyway, because the action picks up rather quickly after past-Thanos makes his way to the present.

Steve Rogers’ Pym particles

While we’re at it, let’s also discuss Cap and the number of particles he takes with him while going on a mission to return all of the Infinity Stones and Mjolnir.

He has to visit, in whatever order he deems necessary, 1970, 2012, 2013, 2014, and the year where he decides to settle down with Peggy. He can probably plan an efficient way of doing it, but if he needs to jump at least five times in the past, that means he should have either three or six vials of Pym particles. Like I said before, it’s unclear if one Pym container is enough for a round trip, or if each trip requires a new vial. The movie doesn’t show them exchanging vials, so I’d say that each container is suitable for one round trip, because they show Lang wasting one during testing.

Image source: Marvel Studios

We also know that Rogers stole four Pym particle vials from 1970 out of the 11 we see in Hank’s lab. Tony needed one, which leaves Cap with three others. Now, he uses either half a Pym particle or a full one to return to 2023 from 1970, so he has two extras. That means, best-case scenario, he has five trips left (five half-vials). Worst case, two Pym particles get him only two trips. 

In other words, it sure looks like Cap might need more Pym particles to get the mission done. Either that, or one of the reasons he won’t make it back to 2023 is that he ran out of resources.

But, if you think about it, with Hank alive, they could have made as many Pym particles as needed. Marvel never tells us.

The Tesseract

When “Howard Potts” took the Space Stone from S.H.I.E.L.D. in 1970, it still had the same cubic Tesseract form we’ve grown to know. But when Cap takes it back, the Space Stone is placed in a suitcase. How exactly is he going to turn it back into a Tesseract-like device? It’s a simple detail, but one that matters. It’s one detail that could create a brand new timeline back in 1970, one where S.H.I.E.L.D. finds out that the Tesseract is housing an Infinity Stone long before they are supposed to. Maybe this is the timeline where Cap settles down.

Image source: Marvel Studios

Soul Stone

I’d sit for another three hours without peeing just to see Cap return the Soul Stone to Vormir. Because it’d be so awesome to hear Red Skull greet him — “Welcome, Steve Rogers.”

More seriously, however, this is the first time that we’ve seen someone return a Stone voluntarily. Given that the Soul Stone is still in mint condition, shouldn’t Steve get something in return for it? Like, maybe Nat? Whatever the case, the Soul Stone needs to be returned, because these Infinity Stones are crucial for the existence of each timeline.

Captain America’s shield

Let’s stick with Cap, because we have no idea where his shield at the end came from. Yes, Rogers had one made, and he either saved it all these years while waiting for this moment, or he brought it from a different timeline. Marvel doesn’t explain, but it’s clear that they want to keep the Captain America role in place. This brings us to…

Captain America’s fate

We’ve established how Marvel time travel works. Past events can’t be modified to change the present. Messing with adverse events in the past, however, will create a different timeline. Marvel doesn’t explain what Steve has done after returning all the Infinity Stones to their proper places.

Image source: Marvel Studios

He either stayed in the MCU-timeline without affecting anything that happened in the past, to not cause a split, and therefore was able to live his life with Peggy and survive until 2023. But how did he know he’d live long enough to pass on his shield?

The other possibility is for Steve to be Steve, settle down with Peggy while dealing with the bad things that happen in his future (our past), and create a new timeline. In this case, however, he’d have to return to the MCU-timeline using the suit and Pym particles, in which case he’d have to reappear inside that mini Quantum Realm tunnel, not on a bench.

Life without Infinity Stones

To get into this, let’s recap what The Ancient One told Hulk when he asked to borrow the Time Stone (emphasis ours):

If I give up the time stone to help your reality, I’m dooming my own. […]

The Infinity Stones create what you experience as the flow of time. Remove one of the stones, and that flow splits, now this may benefit your reality, but my new one, not so much. In this new branch reality, without our chief weapon against the forces of darkness, our world will be overrun, millions would suffer. So tell me, doctor, can your science prevent all that?

She was thinking, of course, mostly of the Time Stone, which is one of the essential weapons a Sorcerer Supreme posses. It wasn’t a coincidence that she was wearing one during the Battle of New York.

But if everything The Ancient One told us about the Infinity Stones is true, how is our MCU-timeline going to survive without Infinity Stones? Let’s not forget that Thanos destroyed them five years ago, yet the universe was left standing. Marvel has to tell us what happens down the road if a timeline doesn’t possess any Infinity Stones. Not to mention that Doctor Strange will probably not have a Time Stone in Doctor Strange 2.

This is the biggest plot hole of the movie, in my opinion, given the quote above.

One huge question

I did tell you at the top of this post that I have seven plot holes and one huge question. That question is: Why didn’t they go to 1970 for more Pym particles to begin with?

Marvel clearly wanted to limit time travel, but come on! We’ve got a bunch of brilliant minds who could have gone either to 1970 and/or 2015 to grab Pym particles from the past, even if that meant talking to Pym himself or Darren Cross about it (remember, Cross managed to replicate Pym’s particle back in 2015).

Image source: Marvel Studios

We’ve already explained that messing with the past doesn’t change the future. Instead, it creates additional timelines. So why not get more Pym particles first, to ensure they have a multiple chances to succeed?

Marvel insisted on the careful planning of the mission, from Tony Stark going in only once he knew it could be done safely, to recruiting as many team members as possible to ensure success, to making sure they all know exactly what to do and where to go. But none of these brilliant minds on the team thought, even once, to go grab more Pym particles from the past — or even spend time in an alternate universe to make them themselves. After all, Tony Stark came up with a brand new element in Iron-Man 2, so he could probably come up with more Pym particles all by himself, given that whatever is left of S.H.I.E.L.D. must know a thing or two about Pym’s research.

It’s possible that their state of mind may have prevented them from thinking about stealing Pym particles before getting the Stones, but it’s still incredibly surprising for some of these heroes not to consider this option.

Chris Smith Senior Writer

Chris Smith has been covering consumer electronics ever since the iPhone revolutionized the industry in 2008. When he’s not writing about the most recent tech news for BGR, he brings his entertainment expertise to Marvel’s Cinematic Universe and other blockbuster franchises.

Outside of work, you’ll catch him streaming almost every new movie and TV show release as soon as it's available.