Could 'Avengers 4' Involve A Time Travel Plot? [Updated]

Update: A new photo from the set of Avengers 4 offers an alternative theory to time travel. See more below.

The plot of Avengers 4 has remained tightly under wraps – we don't even know the title! But as the comic book movie sequel continues production, secret plot details have inevitably begun to surface.

Since Avengers 4 started production in August 2017, there have been some exciting snapshots of new costumes, gnarly hair cuts, and lots of grim-faced Marvel superheroes. But the most intriguing picture of all — a set photo of Chris Evans in a familiar costume — could have wide-ranging implications for the plot of the fourth Avengers movie, and the Marvel Cinematic Universe movies that follow it.

Warning: Possible spoilers for Avengers: Infinity War and Avengers 4 follow.

What does the future of the MCU look like? A little retro, to be honest. On Wednesday TMZ released a photo of Chris Evans on the set of Avengers 4, clean-shaven and wearing his old Avengers-era Captain America suit. It's a patriotic outfit that Steve Rogers had shed long ago, since he started working for S.H.I.E.L.D. in Captain America: The Winter Soldier. He later repurposed his old World War II fighting outfit, but he never went back to that "old-fashioned" stars and stripes get-up from the first Avengers.

So why is he wearing it in Avengers 4? Well, the most obvious answer would be: time travel.

Yes, that does seem like a huge leap of an answer to a makeover, but like a certain 2017 movie wisely said, Marvel has been giving us all the clues. Nerdist first picked up on it after combing through the costume changes and mysterious Robert Downey Jr. Instagram pictures back in December. First, there was an online photo from Downey Jr. featuring a hole in his shirt for the arc reactor that Tony Stark used to have. Jeremy Renner was seen sporting a costume that looked eerily similar to Hawkeye's Ronin persona that he may have adopted in a future or altered timeline. Casting calls have been made for scenes possibly set in the '60s and '40s. Captain Marvel, whose solo film is set in the '90s and deals heavily with the quantum realm, will make an appearance in Avengers 4. And Ant-Man and the Wasp, which is also centered around the quantum realm, is reported to have a major impact on the events of Avengers 4.

It all adds up to more than just a few flashbacks. This could mean a whole Back to the Future-style plot where the team jumps through time and space, attempting to change history itself.

Okay, this is the part where the theorizing starts. Put on your tinfoil hats.

Avengers 4 will very likely follow Thanos beating the Avengers and finishing the completion of the Infinity Gauntlet, scattering the team into alternate timelines or dimensions in the process. The story could follow them going to key moments in history — the battle of New York in the first Avengers film, the '90s when Captain Marvel first gains her powers — and attempting to change its course. Or they could be attempting to foil Thanos' early grasps for the Infinity Stones. This could be a result of the Time Stone that we were first introduced to in Doctor Strange, which Stephen Strange used against Dormammu, or the Avengers could be making use of the quantum realm — a dimension that transcends time and space.

If Avengers 4 does indeed have a time travel plot, this opens up infinite (pun intended) possibilities for the MCU. This could be the universe-shattering event that Kevin Feige and the Anthony and Joe Russo have been hinting at, a whole new chapter for the MCU that involves not just the cosmos, but alternate worlds and alternate dimensions.

A new photo emerged from the set of Avengers 4 showing the Russo brothers and a crew member carefully managing an orange box with the label "Binary Augmented Retro Framing." Sound familiar? It should — Binary Augmented Retro Framing, or BARF, was featured at the beginning of Captain America: Civil War during Tony Stark's presentation of a new technology that allowed him to revisit a memory with teen him and his parents. The scene mostly made waves for its use of digital effects to de-age Robert Downey Jr., but this unexplained reappearance on the set of Avengers 4 could suggest a greater significance.

So what could this mean? Heroic Hollywood points out that the scenes we see of younger Captain America could simply be artificial memories projected by BARF — not time travel. But that doesn't completely explain other sightings on set (Hawkeye's new outfit for one), but it's an intriguing theory.

Avengers 4 is set to hit theaters on May 3, 2019.