The previous Captain America feature, Civil War, released about 9 years ago. That was the last narrative where Thunderbolt Ross had a substantial role in a Marvel Cinematic Universe plot, and his Sokovia Accords are mentioned in Brave New World’s dialogue. Ross locking up Sam, Ant-Man, and Hawkeye is also discussed in the film, as well as the politician designating Captain America, Falcon, and Black Widow as fugitives – we see they are Secret Avengers in Avengers: Infinity War.
The place that superbeings are imprisoned in is called The Raft, sitting in the middle of the ocean. By the end of Brave New World, the tables turn and Ross/Red Hulk is now a prisoner at the Raft, along with the true agitator in the storyline, Samuel Sterns, a.k.a. The Leader.
Sterns hasn’t been seen since the 2008 solo Incredible Hulk movie, where Banner’s blood accidentally oozed into an open cut on his temple, changing him into the villainous Leader wreaking havoc in this film. That was the same movie that introduced Thunderbolt Ross, only he was played by the late William Hurt, also appearing in Captain America: Civil War, Avengers: Infinity War, and Black Widow. He can additionally be spotted at Iron Man’s funeral in Avengers: Endgame. Liv Tyler reprises her role as Betty Ross, and like Tim Blake Nelson’s Leader, her only previous MCU attendance was in The Incredible Hulk.
Several conversations around what took place between Hulk and Abomination are brought up, as well as a clip of the rumble in Harlem. Exposition is filled in as to what occurs between Sterns and Ross from that time period to now. The song that Leader uses to hypnotize others to follow his orders is called “Mr. Blue”, which was his code name in Incredible Hulk when stealthily communicating with Bruce Banner; Hulk’s alias was Mr. Green.
From one MCU standalone movie to another, the climax of Eternals is finally publicized to have some significance in the broader franchise. After all, a giant Celestial became petrified midway from emerging from the center of the Earth, leaving his head and hand in the Indian Ocean. Brave New World details the research that was conducted by various nations and the discovery of Adamantium.
Adamantium is the same indestructible metal that is fused to Wolverine’s skeleton, and since Deadpool & Wolverine exposes that Wolverines are abundant across the multiverse, can we assume that Logan (or at least the version of him that becomes the mutant Wolverine) does not exist in MCU’s prime Earth-616. The Marvel series has been bringing mutants into the fold, little by little, from alternate reality sightings of Professor-X and Beast, to the revelation that Ms. Marvel possesses the X-gene. Brave New World’s Adamantium is another hint of the X-Men’s proper arrival in the MCU.
Despite the awesome associations with other MCU works, and especially all of the links to The Incredible Hulk, Brave New World is a definitive Captain America event. Even though Steve Rogers gifted Sam Wilson the shield at the end of Avengers: Endgame, there was an entire limited series dedicated to charting Sam’s path to actually “becoming” Captain America. In The Falcon and the Winter Soldier, Sam worked beside Bucky Barnes to take down international threats. The Winter Soldier pays the new Cap a visit in Brave New World. This marks Sebastian Stan as the only MCU actor to appear in all four Captain America movies.
In the show, Joaquin Torres joined Sam as a sort of sidekick and now he has graduated into a superhero of his own, replacing Sam as Falcon. Torres jokes to Sam that he wants Cap to introduce him to Ant-Man, which is a nice tie-in to Sam’s history with the astonishing hero – Wilson (as Falcon) was the only Avenger to drop in on Ant-Man’s own sub-franchise.
The other supporting character to make the jump from the Disney Plus series to Brave New World is Isaiah Bradley, sometimes referred to as the original black Captain America. He has a pivotal part to play in the movie. When Sam and Joaquin first meet up with the super soldier, Isaiah knocks a punching bag across the room, the same way the first super soldier, Steve Rogers, does when approached by Nick Fury at the beginning of The Avengers.
There is also a Wakandan connection in The Falcon and the Winter Soldier, thanks to Bucky’s background with the region and their people. He was a resident of the secluded country post-Civil War, leading in Infinity War. The Wakandans built Bucky an improved Vibranium arm and now we see they provided Cap with new Vibranium wings for Brave New World.
Just like Black Panther’s Vibranium suit, Sam’s tech can absorb energy and redirect it outward; this functionality comes with a glowing purplish signature. This upgrade does give Cap an advantage when fighting, but he still questions if he should have taken the super serum when he had the chance in The Falcon and the Winter Soldier, which would have been particularly useful when facing off against Red Hulk.
Although the fourth Captain America's plot points sequentially follow all of the narrative seeds planted in these numerous movies and shows, at its core, Brave New World most closely resembles Captain America: The Winter Soldier. The political thriller tone is consistently present in both, with a government infiltration flowing throughout Winter Soldier, and a conspiracy to topple the presidency in Brave New World.
There is also a trio that forms between Captain America, Falcon, and a Black Widow. In Winter Soldier, the quintessential version of all three team-up, while the new release has the replacements for Captain America and Falcon work with a former Red Room occupant; Sabra is notably referenced as a Black Widow. Lastly, in The Winter Soldier, Alexander Pierce brainwashes Bucky – the mastermind behind the scenes sends the dangerous operative out to do the dirty work. There is a very similar scenario at play in Brave New World, with Leader pulling the strings, controlling others' minds and unleashing the Red Hulk.
There is also an after-credits scene that teases what is to come for the MCU. Leader prophesizes a huge multiversal threat, likely to take shape in the upcoming Avenger epics, Doomsday and Secret Wars. President Ross proposed that Sam Wilson lead a new Avengers team and Brave New World is tagged with the statement that Captain America will return.