the greatest films ever made, but that doesn’t mean its logic is completely sound. As with any film where time travel plays a major role in the story, audiences have discovered certain plot holes and inconsistencies over the years that raise important questions about the story’s integrity.

Some of Back to the Future’s biggest plot holes have been fixed in the decades since the film’s release, but others remain particularly difficult to resolve. While it’s difficult to take most of these paradoxes seriously given the goofy and comedic tone of the story, certain aspects just don’t add up after multiple viewings. One of the biggest and most incalculable paradoxes seems to imply that Doc’s time travel caused infinite versions of Marty McFly to exist at the same time.

Back To The Future’s Second Marty McFly Paradox Explained

The Paradox Raises Questions About How Time Travel Works

This crucial Back to the Future paradox has been around for just as long as the movie itself, and it poses some major issues for the movie’s timeline. The problem is as follows: when Marty returns from 1955 at the end of the movie, he visits the Hill Valley parking lot where his past self saw Doc Brown get shot and subsequently used the DeLorean to travel back in time. Upon first glance, this seems like a closed loop; Marty travels to the past, saves the day, comes back, and watches his past self embark on the same journey.

However, the Marty in the parking lot at the end of Back to the Future (aka “Marty 2”) isn’t the same Marty that we saw at the beginning of the film. He’s an alternate version of Marty from a new timeline where his family is happy and rich. So, when Marty 2 travels back in time, it can’t be expected that his journey will be exactly the same as Marty 1’s.

To make things even more complicated, Back to the Future explicitly states that only one timeline is changed when the past is altered, implying that all these Martys co-exist in 1955 at the same time.

He will almost certainly do things differently, potentially altering the timeline again, and when he returns to Hill Valley in 1985, the Marty that he watches in the parking lot will be another version altogether, resulting in Marty 3. To make things even more complicated, Back to the Future explicitly states that only one timeline is changed when the past is altered, implying that all these Martys co-exist in 1955 at the same time.

Doc Brown Set The DeLorean To Get Marty 2 Killed – Theory Explained

This May Have Been The Only Way To Prevent The Paradox

Thankfully, one fan theory completely changes Back to the Future’s meaning and seemingly explains how Doc Brown could prevent the infinite Marty paradox. The suggestion posits that Doc realized he was in the altered timeline (perhaps thanks to Marty’s letter), and foresaw the consequences of sending Marty 2 into the past. This forces him to change the coordinates on the DeLorean and send his friend to a location from which he would never return. This would effectively close the loop and ensure that no more Martys returned from 1955.

This is an extremely dark version of the story, and it goes against everything that Back to the Future suggests about Doc’s personality, but it may have been the only way to prevent a multiversal collapse.

One variation of this theory even suggests that Doc Brown changed the settings on the DeLorean to explode and kill Marty before he could accidentally cause another timeline to diverge. This is an extremely dark version of the story, and it goes against everything that Back to the Future suggests about Doc’s personality, but it may have been the only way to prevent a multiversal collapse.

How To Solve The Multiple Marty McFlys Problem Without Killing Marty 2

The Paradox Only Exists If Doc Brown Was Right About The Multiverse

There are some noticeable mistakes in Back to the Future regarding the film’s logic, so this paradox should be taken with a pinch of salt. Of course, it’s possible that Doc Brown’s understanding of time travel was inaccurate, and multiple timelines branch off each time Marty goes back to the past. This would create an infinite number of new realities that are constantly evolving, but it’s an easier solution than imagining an infinite number of Martys existing at the same time.

This theory is much harder to believe since it doesn’t explain how Doc Brown was able to prevent his own death, but it’s easier to stomach than Doc intentionally killing Marty, given their bond in Back to the Future.

It’s also possible that certain changes to the timeline don’t happen at once, and Marty’s first journey in the DeLorean is kind of a “fixed” moment that’s constantly happening to bind the timelines together. This would mean that Marty 2 is really just Marty 1, and the scene plays out the same way every time, regardless of changes to the timeline. This theory is much harder to believe since it doesn’t explain how Doc Brown was able to prevent his own death, but it’s easier to stomach than Doc intentionally killing Marty, given their bond in Back to the Future.