From the DeLorean to Marty McFly's orange vest, everything about Back to the Future is iconic in popular culture. The adventures of Marty McFly and Doc Brown as they travel through time are endlessly rewatchable, and repeat viewings have fans doing a deep dive into the nuances of the story.
As a sci-fi franchise about time travel, there are many unanswered questions and elements about Back to the Future's plot which audiences have been pondering for decades. As such, these questions have spawned a multitude of fan theories that could potentially change how everyone views the series forever.
George McFly Knew Marty Time Traveled
In the first movie, Marty is stuck in 1955 and accidentally messes up the timeline. To fix it, he enlists the help of his father, George. But this has led to a prominent theory that, once Marty returns to 1985, George knows about his time travel adventure.
During their conversations and interactions, Marty names or references multiple futuristic things, such as Darth Vader, Calvin Klein, and an incident involving the McFlys' carpet being set on fire. Given that George is an avid sci-fi fan as well as a writer, it would make perfect sense for him to realize that "Calvin Klein" from 1955 was actually his son from the future. But knowing how tricky time travel is when it comes to paradoxes, he wouldn't mention that he knows about Marty's time-traveling shenanigans, explaining why he never says anything.
Doc Brown Murders Marty
Back to the Future may be one of the least complicated time travel movies, but there still are some confusing elements, such as the loop created in the first film that still exists when Marty returns from 1955. This loop, in which Marty sees himself escape the Libyans and travel back in time, is the subject of another darker theory.
Since Marty changed the timeline in 1955 so that George became a success, this new timeline's Marty would have a different upbringing. The theory states that Doc Brown rigged this new time machine to burn up upon traveling through time, killing the new timeline's Marty. He does this knowing that the Marty he met in 1955 would shortly return, letting him still have the ability to travel through time while closing a time loop at the same time.
Doc Changes Time To Save Marty From Biff
Back to the Future Part 2 is a sequel movie many consider better than the original, but that doesn't mean that it's not free from dark fan theories about the plot.
This theory involves the scene in which Marty, on his hoverboard, is being chased down in a tunnel by Biff in his car. At the last second, at the end of the tunnel, Doc arrives in the DeLorean and saves Marty. But the theory says that, originally, Biff succeeds in running Marty over and, in order to save his friend, Doc travels back in time to rescue him. This theory also explains how Doc would know where Marty was and when to fly in to save him, something that fans have been questioning for years.
Doc's Views On Time Travel Change
Doc has always been rigid in his views about altering the timeline, never wanting to change it for fear of the consequences it could bring. However, one theory states that Doc's views may have secretly changed by the end of the first movie.
In the scene at the end when Marty is about to go back to 1985, he tells Doc what happened at the dance and that George punched Biff out, which is a change in his character. Doc seems startled by this, but simply moves on. At that moment, according to the theory, Doc realizes that not all changes to the timeline are for the worst; some could be for the better, such as Marty's family life improving. This is why he doesn't protest this change in the timeline and lets it continue, knowing that this change isn't a bad thing.
The Sports Almanac Can Change Like Marty's Picture
The sports almanac that Marty buys in the future causes no end of trouble when Future Biff steals it and gives it to his younger self in 1955. But it might be more powerful than anyone thinks.
Based on the time travel rules of the franchise, should history be changed, the almanac would also change to reflect the alteration to the timeline, much like Marty's picture in the first film, which changed based on the change in the timeline. This makes the almanac insanely powerful and almost impossible to beat, unless someone made a change in history after a bet is placed, which would potentially cause more paradoxes — and more headaches for everyone involved as they try to figure the whole thing out.
Doc Invented Present-Day Technology
There are many reasons why some consider Back to the Future Part III the best movie in the franchise, but Doc's presence in 1885 may change the future in ways he never intended, according to this theory.
Doc is an inventor, and he's already invented several things in 1885 that shouldn't exist, such as a refrigeration unit that makes ice. According to this theory, this already alters the timeline so that innovations like this are discovered quicker, making further technological advancements such as the massive tech leap by the time 2015 hits more likely and possible. Though Doc has strict rules about not altering the timeline in any way, this apparently doesn't apply to him making life easier for himself in 1885, changing the timeline in the process.
The Lockard Theory
In a series of movies filled with Chekhov's gun moments, viewers are bound to pick up on some parallels between the movies. But this theory shows how the entire story mirrors itself from beginning to end, also known as a chiasmus.
This theory, named after its creator, Robert Lockard, suggests that the entire franchise is symmetrical in its story. How it begins is also how it ends, and each major plot point is reflected at one point or another. For example, the franchise opens with Marty getting blown away by an invention of Doc's, something that also happens at the trilogy's conclusion. The DeLorean's debut and demise also end in the exact same way, with the license plate spinning out on the ground. The Lockard Theory is extremely complicated, but those who understand it just might see how true it really could be.
The DeLorean Itself Can't Make Paradoxes
The star of the show of the franchise is, of course, the time-traveling DeLorean. And while its importance is obvious, one theory shows the belief that the DeLorean might be helping prevent major paradoxes.
Citing the multiple times in which something happens to the DeLorean that prevents supposed paradoxes from taking place, the theory states that the DeLorean itself ensures that no paradoxes can occur and jeopardize the timeline. For example, in the first Back to the Future, upon returning to 1985, the DeLorean promptly stalls again, preventing Marty from getting back to Doc in time to "save him" and run into his alternate self, which, according to Doc, would create a paradox. The theory cites multiple times in which the same thing occurs: the car breaks down, preventing a paradox from occurring, almost as if the car itself is stopping reality from becoming undone.
Marty Had Second Thoughts About The Letter
In the first Back to the Future film, Marty writes a letter to Doc warning him about the future — a letter Doc promptly rips up. However, he eventually tapes it back together and reads it, leading to his survival.
But viewers have noticed one key thing about this second, taped-up letter: the handwriting is different. This has led to the theory that Marty had doubts about writing the letter in the first place, obviously considering Doc's words that to know one's own future could change everything drastically. According to this theory, Marty is so conflicted that he tears up his original letter before deciding to save his friend, no matter the cost, leading him to write a second letter. It's this second letter that viewers see him giving to Doc, explaining the different handwriting.
Doc Time Traveled Before Marty
In Back to the Future, Doc invents time travel and tests it on his dog before Marty accidentally tests it himself when running from the Libyans. But according to this theory, Doc has already tested the DeLorean and proven that it works.
This theory describes how Doc, in the '60s, was really successful and managed to invent time travel. But upon testing it by going to the past and returning, he changed the timeline and is now an unsuccessful, disgraced hermit. Unhappy about the way things went, Doc decides to try and change the past again. But, thanks to interference from the Libyans and Marty, the Doc from the past is tainted by knowledge from the future, tests time travel out himself early, and ends up burning down his estate like several newspaper clippings seen at 1985 Doc's place. It's a theory so complicated it just might actually be true.