Number Five enjoyed his own Captain America moment in Avengers: Endgame.
The Umbrella Academy season 2 also features a time travel apocalypse story, albeit one with considerably more talking goldfish, Swedish assassins and excessive flatulence. The second season of the Netflix series sees the Hargreeves siblings trapped in the 1960s, and Number Five is desperate to find a way home before yet another apocalypse destroys the world. Having already failed in this endeavor using a time-crossing briefcase directly from The Commission, Five has a flash of inspiration, realizing that his final timeline stop before going home was the Kennedy assassination. Five could find his younger (but physically much older) self and take his briefcase instead.
It's a seemingly foolproof plan, with both versions of Five theoretically wanting the same thing. Unfortunately, meeting oneself in the timeline comes with seven increasingly nasty side-effects, including irrational paranoia and homicidal rage. Unwilling to trust himself, the old and young Number Fives begin pounding each other (and Luther's testicles) into a fine dust. The Avengers: Endgame reference comes as Kid Five and Old Man Five are fighting, with the latter asking "getting tired yet?" and his opponent replying "I can do this all day."
Not only is this a nod to the Captain America of the Marvel Cinematic Universe, but the line alludes specifically to Avengers: Endgame. In the 2019 film, Cap is one of the team who travel back to the Battle of New York, and when the heist goes awry, he ends up fighting his younger self. While it's the older iteration who walks away victorious, the Steve Rogers of the past takes this opportunity to use his "I can do this all day" catchphrase during the battle. The jaded, unimpressed response given by the older Rogers proves to be one of the MCU's most memorable Captain America moments.
The situation is completely mirrored by The Umbrella Academy season 2. As with Avengers: Endgame, two different eras of the same character are locked in battle after attempts to save the world using time travel don't play out as smoothly as hoped. Noting the similarities between Number 5's story and Captain America's, The Umbrella Academy clearly couldn't resist including a more overt nod to the Marvel character in their own doppelganger fight sequence.
The Umbrella Academy's second season is packed with great references and Easter eggs, some of which play on the 1960s era, and a few that take a more meta perspective, like the Captain America line. Diego drops a Star Wars reference, a cinema sign uses film titles to indicate the changing era, and Klaus uses TLC and Backstreet Boys lyrics as part of his cult teachings. Netflix's The Umbrella Academy has always thrived on pop culture to a certain extent, but the shout-out to Avengers: Endgame perhaps shows that even dysfunctional superheroes look up to their Marvel counterparts.
