The first trailer for Avengers: Endgame contains several callbacks to past movies in the Marvel Cinematic Universe. Featuring each of the original six Avengers, with snippets of Nebula, Ant-Man, and the mighty Thanos for good measure, the first footage from Avengers: Endgame sets up a massive climax for the MCU, with some subtle nods to the road that led viewers here.

Indeed, audiences can be sure that Avengers 4 will honor the MCU's 10+ years so far with a cavalcade of references and Easter eggs, in addition to the arcs and story threads that are tied up as Earth's Mightiest Heroes square off with the Mad Titan in one last battle.

Related: Avengers: Endgame Trailer Breakdown - 30 Story Reveals & Secrets You Missed

Going by Avengers: Endgame's first trailer, Marvel Studios wants to remind fans of every step that's been taken by these iconic characters, throughout their various solo movies and team-up blockbusters, as they come together for what might be the last time. And so, the new trailer hints at several of those past films.

Captain America: The First Avenger

Steve Rogers can be seen holding a compass with an image of Peggy Carter identical to the one he had when he crashed the plane at the end of Captain America: The First Avenger. Peggy and Steve's relationship is one of the great tragedies of the MCU, as they are two lovers separated by time and circumstance in a universe whose heroes are constantly forced to sacrifice their happiness for the greater good.

Nobody could've known in 2011 just how monumental Steve Rogers would become in the MCU, not to mention Peggy Carter herself, who received a solo TV show for two seasons before leaving the franchise behind. But with all the evidence of time travel in Avengers 4, it seems that it's possible Captain America will be heading back to the 1940s to meet Peggy one more time.

Captain America: The Winter Soldier

Having presumably been re-instated in good stead with the American government after his efforts against Thanos, Steve has once again donned his Captain America uniform, but instead of the classic version from The Avengers, he's wearing the darker variation last seen in Captain America: The Winter Soldier.

Related: Marvel Has Released An Official MCU Timeline

Using the dark blue outfit befits where Steve's at thematically – he's now lost everyone he knew from his old life, so wearing the modern attire as opposed to the bright red, white, and blue from his World War II days is a sign that he's living in the present rather than the past, no matter how much it might hurt. Plus, in keeping with the time travel theories, it's possible Captain America may also be heading back to 2014, hence why he's also clean shaven in the trailer.

Iron Man 1

Perhaps the most intriguing element of the Avengers: Endgame trailer is Tony Stark's situation, being left stranded out in space with no hope of survival. Tony, seemingly all alone (save for Nebula), leaves a message for Pepper Potts on his heavily damaged suit helmet, resigning himself to death due to almost depleted resources. Going all the way back to the movie that started it all, Tony is wearing the same kind of singlet he was in the cave in 2008's Iron Man, complete with arc reactor glowing out of his chest.

It's a heavy-hearted history lesson for fans, as despite Stark's incredible fortitude for surviving desperate situations, being stuck in the middle of the galaxy with only a day's oxygen left is a steeper challenge than being trapped in a cave. Granted, he has a ship filled with all sorts of technology at his disposal, so the billionaire playboy seems to have accepted that he just won't be inventing his way out of this one. Then again, none of these characters are to be counted out, not least when all chips are down and all hope is lost.

Avengers: Endgame is promising an all-bets-off blockbuster end to the three-phase story arc Iron Man put in motion, and with that anything is possible, even Steve Rogers getting another chance to be with Peggy, or Tony cheating death while floating through the stars.

More: Avengers 4: Every Update You Need To Know

Key Release Dates