Now, I know what you're thinking. The Martian is based off of a book! It can't be part of the Marvel Cinematic Universe! It wasn't even produced by Marvel Studios! Well before you call me crazy, I want you to read this article with an open mind. My theory may be somewhere on the crazy scale between YouTube conspiracy videos and Room 237, but it makes sense. Now sit back, relax, and prepare to have your mind blown.
In the first scene, we see most of the crew of the Ares III mission doing their usual astronaut stuff on Mars. Then, the screen cuts to two more astronauts in the Hab by the names of Beth Johannsen and Christopher Beck, played by Kate Mara and Sebastian Stan, respectively (pictured below).
As a huge comic book movie fan, I instantly recognized these actors as Bucky Barnes (Sebastian Stan) and Invisible Woman (Kate Mara). The wheels in my mind started spinning. What are an Avenger and a member of The Fantastic Four doing on Mars? Probably looking for an Infinity Stone, but we'll get to that later.
Near the climax of the movie, Johannsen kisses Black on his helmet. In the epilogue, viewers see that the two astronauts actually have a baby together. What are the odds that the two super-people in this movie would end up together? As an amateur conspiracy theorist, I do not believe in coincidences. I believe that these actors were cast as Johannsen and Black because even though normal people cannot relate to their amazing abilities and tragic pasts, they can, which is why they end up together.
Another more subtle casting decision also caught my attention: Donald Glover as Rich Purnell. Purnell is a nerdy/genius astrophysicist who ultimately saves the day when his plan to save Mark Watney is successful. This got me thinking; what nerd was Glover rumored to play before Andrew Garfield was confirmed? That's right.
Fans were pushing for the Community and rap star to play Spidey in The Amazing Spider-Man movies as well as the Spiderman currently being portrayed by Tom Holland in the MCU. My original thought of Glover's role in The Martian was as Spiderman, being that The Martian was made before Holland was confirmed for Civil War.
Then, literally only hours after watching The Martian for the first time and formulating my thoughts about its ties to the MCU, Glover was confirmed to be cast as an unrevealed role in Spider-Man: Homecoming, which makes his involvement in The Martian even MORE intriguing. Who can he be? Is he a high school friend (or enemy) of Peter's that also attended Midtown High School? Whoever he will be playing, the fact that he will definitely be in the MCU is very, VERY interesting.
I'm sure you are asking yourself, "but if these characters are who you think they are, why don't they go by their names, Bucky Barnes, Sue Storm, etc?". Well there are a couple of reasons they would not go by their real names. One explanation is that Bucky, Sue, and Glover's character were brainwashed by the US government to forget about their past and dedicate their lives to NASA. Another, more reasonable explanation is that their identities are being kept highly confidential, so confidential that even the rest of the Ares III crew do not know about Bucky and Sue.
How the Plot Ties Into The MCU
Keep in mind that the book is set in the 2030's, so the plot of the movie should not tie into what is currently happening in the MCU, but rather what might occur about 20 years down the timeline, in later phases
So now that we have established that 3 out of about 12 notable characters in the movie are from the MCU, how does The Martian tie into the MCU? Well let's start from the beginning. The crew of the Ares III are on Mars, doing their thing, when suddenly a storm, which arrived sooner and is stronger than expected, forces the crew to abort the mission, leaving Mars along with poor Mark Watney (Matt Damon). How did NASA, especially 2030's NASA, underestimate such a storm? There is only one explanation.
That's right. The X-Men are in space. For a reason that is not 100% clear yet, the Avengers, Fantastic Four, and the X-Men are all in space. I would assume that they are looking for Infinity Stones, but it could be for a number of reasons.
Another clue that the X-men go into space actually comes from another movie, Wolverine (2013), which is also set in the not-too-distant future. When Logan (Hugh Jackman) and Mariko (Tao Okamoto) check into a romantic motel, they stay in the "Mission to Mars" room. When they walk into their space-themed room, Logan says "This'll do... kinda home-y actually". If that line and the name of the room do not convince you that the X-Men go into space, then I don't know what will.
Given that a dangerous storm came out of nowhere and that Logan practically told us that he has been in space, it is very reasonable that Storm is the one who kicked NASA (along with Bucky and Sue Storm) off of Mars, where the X-Men are either stationed or are looking for something or someone (most likely Infinity Stones).
The Easter Egg Of All Easter Eggs
While I was watching the movie, I had my doubts whether or not this theory was actually possible. Then, in the climax of the movie, I had all the confirmation I needed.
As Watney was preparing for his rendezvous with the rest of his crew, he had to figure out a way to get closer to his commander. He had the idea to puncture a hole in his suit which would project him in any direction he wanted if he were able to control it. While his commander tells him that this is a bad idea, Watney replies, "I'd get to fly around like Iron Man". I was so excited to hear this line come out of Watney's mouth, confirming my suspicion that this movie is in fact in the MCU.
After doing some research, I learned that this line actually came straight out of the book. Even so, the fact that the screenwriter, Drew Goddard, decided to put the line in the book is meaningful. And speaking of Goddard, did I mention that he is the executive producer of Daredevil and The Defenders, two of Netflix's new wave of Marvel shows?
At the end of the day, I know that it is a real longshot that The Martian is actually part of the MCU. However, given all the Easter Eggs and details I found above, I think that it is very possible that some of the producers and higher-ups at 20th Century Fox had some fun and made a fantastic movie that just so happened to have a lot of connections to the MCU and X-Men universe.