Clever scene in Endgame where future Tony arrives at Stark Tower right after the Battle of New York in Avengers 1. After dismissing everybody for posing too much, the Avengers head down to lobby in the elevator, telling Hulk to take the stairs.

On his way down the stairs (Hulk: "(grrrr) SO MANY STAIRS!!!") Hulk gets infuriated and busts out of the stairwell on the ground floor in the lobby. This action ends up throwing the future-Stark's Tesseract recovery operation.

Wouldn't future Stark have remembered that event, and tried to avoid the timing of it?

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    Originally, he wasn't there. He was arguing/about to argue with Pierce
    – Vishwa
    Commented Aug 28, 2019 at 3:50
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    They're not changing the past. They're visiting a different past, with a different Tony Stark, where Loki escapes with the Tesseract. This never happened in the original timeline.
    – Luaan
    Commented Aug 28, 2019 at 12:46
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    I can't remember what I had for lunch 30 minutes ago, and I don't have as many problems on my head as Tony Stark does at any given moment.
    – Geeky Guy
    Commented Aug 28, 2019 at 16:02
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    Do you really think Tony remembers in detail every time he was a jerk more than a decade ago? That mental power may well be more impressive than any other mental capability he's shown. Commented Aug 28, 2019 at 16:11
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    Yeah, none of the past events are exactly their own past. Otherwise, you'd think Cap would remember getting beaten up by himself, Tony would remember having a heart attack that day, Thor would remember losing Mjolnir right before the big fight in Dark World, etc. It's a parallel timeline, not their actual past. Commented Aug 28, 2019 at 17:50

6 Answers 6


In 2012 Tony took the elevator and ended up in an argument about who should keep the Tesseract. At that time hulk busted out of the stairway and exited the building.

  1. Tony's mind was involved in more important things, like the Tesseract.

  2. He had gotten used to Hulk busting things up now and then, so it was one more of such things.

  3. Tony had lost so many people in 2018 that affected him deeply.

  4. In 2023 Tony travels back to 2012, which means 11 years had passed. This time Tony's focus was to get the hell out of there with the Tesseract.

After 11 years, Hulk exiting from the stairway was a tiny event which Tony doesn't recollect as it didn't affect him in 2012.


There's another element that the other answers haven't addressed:

Not half an hour before the Hulk's stairway-induced rampage, Tony had flown through the Chitauri wormhole and detonated a nuclear bomb. This very nearly killed him and/or trapped him on the wrong side of the wormhole, and Iron Man 3 firmly establishes that the whole ordeal left him with post-traumatic stress disorder.

PTSD, and psychological trauma in general, can affect a person's memory - particularly of the events surrounding the time the trauma was inflicted. Couple in the factors mentioned in the other answers - the 11-year time gap, the other traumas Tony had sustained in the interim, and that he may not even have been paying attention when the rampage occurred - and it's really no surprise to me that he doesn't remember.


Right before the scene, the event happening is a jurisdictional dispute between a God of Thunder and the director of SHIELD, which we know eventually results in the Tesseract going to Asgard. And this dispute had started heating up in the scene we witnessed. It only got interrupted, and allowed for the heist, because past-Tony was given a cardiac arrest, and everyone's attention got diverted.

Without this event happening, and original events proceeding as they originally did, it's entirely plausible that Tony Stark had never originally noticed the incident of Hulk coming out the stairwell at the end in that fashion, at that time. It's also entirely plausible that it didn't register as the significant event of that specific time.

Alternatively: He was so focused on trying to make sure his heist had gone unnoticed that he wasn't paying attention to his exact location in relation to the stairs, or forgot that Hulk was coming down the stairs.

  • Alexander Pierce vs Thor... yeah the Tesseract definitely went to Thor... lol
    – enorl76
    Commented Aug 29, 2019 at 20:22

The other possibility is that Hulk didn't bust through the stairwell in the original timeline. Perhaps a butterfly effect happened between the Avengers arriving in 2012 and when the Avengers get in the elevator.

In the first Avengers movie, we can see Bruce Banner eating shawarma in the end credits scene with the rest of the Avengers. So in the original timeline, sometime between Tony coming back from outer space, and that shawarma scene, Hulk turns back into Bruce Banner. Maybe in the original timeline Bruce Banner enters the elevator with everyone else, and never busts through the stairwell.

Whereas in the new timeline, Hulk has to take the stairs and busts through the stairwell.

Although I agree it's entirely possible that Tony Stark just forgot that Hulk busted out of the stairwell, I think it's more likely that Hulk never busted out of the stairs in the original timeline, and that's why Tony Stark was caught off guard.

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    I hadn't considered butterfly effect only because (on-screen) we never see them interact in any way that could cause a difference. Its after that scene that we start to see some interactions that would definitely start to cause butterfly effects: Cap saying "hail hydra" (all the elevator people now assume Cap is Hydra), to Cap fighting himself (cap possibly remembers a strange encounter with himself for the rest of his days), to Tony Stark posing as Howard Potts and telling Howard Stark "No amount of money ever bought a second of time". Who knows how these things drastically affect "future"
    – enorl76
    Commented Aug 29, 2019 at 22:03

There's much evidence that when they travelled to the past, they created an alternate timeline:

  • This scene with Hulk and the stairs
  • Loki escapes right away with the Tesseract
  • The whole Captain America vs Captain America fight

All of these scenes are incompatible with what we know happened in the first Avengers film.

Also, there's another point in the film, when Bruce Banner goes to the Ancient One to ask for the Time Stone. She actually gives a rather flashy explanation of the timelines and the stones, and how they have to return them to their original timeline so not to destabilize it.

When they build the time machine, they mock Ant Man for thinking it would work like Back to the Future. But, really, it kinda does, since by travelling to the past they create branching timelines that won't necessarily lead to the same future.

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    They directly say in the movie, with no ambiguity, that going to the past creates a new, alternate timeline. We don't need further evidence to know that.
    – user91988
    Commented Aug 28, 2019 at 16:50
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    @arturo, They don't travel to a different timeline. They end up creating an alternate timeline by traveling to the past. So it's safe to say that the two Tony up until that moment in 2012 share the same past. It branches off only after that, like that heart failure that Ant Man causes.
    – MovieMe
    Commented Aug 28, 2019 at 19:01
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    The event in question is Hulk walking down the stairs. That is not a change caused by any event triggered from the time-heisters. Loki and Captain America is a different story, as is what SHIELD thinks about Captain America, but those have nothing to do with the question as asked.
    – DariM
    Commented Aug 28, 2019 at 22:21
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    I'll reword that bit at the beginning, because I generally agree with @MovieMe Commented Aug 29, 2019 at 15:56
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    Back to the Future's timelines converge and erase alternates. I think in the new MCU timeline they had plenty of time to return the stones so as to not cause worse timelines. The comic time is more fragile, though, as seen in Age of Ultron. Commented Aug 30, 2019 at 8:27


They have gone into a different, branching, alternate timeline. There is no reason to believe that Stark would remember this event unless he (or the audience) also know that this event also unfolded in exactly the same way in Stark's past (like if it was shown in a previous movie).

Related dialogue (emphasis mine):

Bruce Banner: Changing the past doesn't change the future.
Scott Lang: Look, we go back, we get the stones before Thanos gets them. Thanos doesn't have the stones. Problem solved.
Nebula: That's not how it works.
Bruce Banner: If you travel to the past, that past becomes your future, and your former present becomes the past, which can't now be changed by your new future.
Nebula: Exactly.
Scott Lang: So Back to the Future is a bunch of bullshit?

As explained by Banner, and as remarked upon by Lang, their actions when they went back to the past (new future) didn't and won't affect their former present (past), so none of them would've "remembered" what happened because those events didn't happen or didn't happen in the exact same way as their past.

We don't know if the Hulk arrived on the ground floor in the same manner and at exactly the same time as the original timeline. We don't know if he even went down the stairs at all because the events shown in Endgame are already after they've arrived in the past (the timeline has already branched).

Thor "remembered" that his mother would die on that day they came back to in the past because this event was shown in Thor: The Dark World. The events: Hulk busting out of the stairwell, past Stark and Thor arguing with Alexander Pierce, among other events, were only shown in Endgame, and not in a previous movie. I've re-watched The Avengers (2012) to verify and those events were not shown in that movie.

In his memoir, Look Out For The Little Guy! Scott Lang (Ant-Man) confirms that they traveled to alternate timelines to collect the Infinity Stones. He writes in Chapter 10: From beginning to endgame:

The idea was, we would identify specific, recent points on alternate timelines where we knew an Infinity Stone to be. And then we’d use the Quantum Tunnel to “jump” to that timeline and grab the stone there. Once in possession of all six, we would have the same power Thanos used to create the Blip—except we’d use that power to bring everyone back.

Unfortunately, once my Tony grabbed the Tesseract case, the Hulk emerged from the stairwell and knocked Tony down. But not my Hulk, the other Hulk. The one from 2012…but, like, an alternate 2012. You know what, let’s call him “Alt-2012 Hulk.”

Alt-2012 Hulk knocked Tony over, the case slid across the floor, and in the end all my distraction did was allow Alt-2012 Loki to escape with the Space Stone. One can only imagine what that led to.

That’s when I uttered a phrase that may as well describe my entire life:

“That wasn’t supposed to happen, was it?”

In other MCU media:

Loki (2021 TV series) expounds on the concept of branching timelines. In Loki, it was revealed that the Loki that took the Tesseract in Endgame is a variant of Loki from a branched timeline and that a person may have multiple variants of themselves, each from their own timelines. From this, it stands to reason that "past" Stark is a variant of the time-traveling "original" Stark. Time-traveling Stark would not have memories of his other variants' experiences, just like Loki didn't have memories of his other variants' experiences.

In Doctor Strange in the Multiverse of Madness (2022), where Strange travels the multiverse and learns of and meets his variants, it was revealed that the Strange variants in the other universes have very different experiences of their pasts and even have very different personalities from the "original" Doctor Strange. Aside from very few, specific experiences, Doctor Strange did not "remember" his other variants' experiences.

  • This is the right answer. The movie went to great lengths to explain that time travel does not work like that yet people still persist on applying Back to the Future logic to the storyline. Commented Aug 30, 2019 at 11:37

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