Captain America: The First Avenger Almost Had A Totally Bonkers Climax
By this point, the end of 2008's "Captain America: The First Avenger" is an iconic part of MCU history. Wrapping up Cap's first story with the reveal of the Tesseract, the foreshadowing of Red Skull's appearance in "Infinity War" years later, and Steve Rogers' subsequent time in the ice, the climax does a lot for the MCU as a whole. However, this series of events wasn't the original plan for how things would play out.
In an interview with Yahoo! Entertainment, writers Christopher Markus and Stephen McFeely looked back on the film for its most recent anniversary. They discussed several things, from Sebastian Stan's audition for Steve Rogers to the mystery surrounding Cap's virginity across the series. One of the biggest takeaways from this, however, was the original climax they had planned for the film. Without revealing too much, "Captain America: The First Avenger" almost had a wild climax that gives meaning to the term "over the top."
Steve Rogers originally had to fight a comically-threatening Nazi-bot
According to Markus and McFeely, the ending to Steve Rogers' first story wasn't always so simple. In the final version of the film, Cap and Red Skull duke it out on a Hydra aircraft carrying the Tesseract. Cap wins, Red Skull is teleported via the Tesseract to an unknown location (later revealed to be Vormir), and Steve Rogers is forced to bring the plane down in the Arctic, where he remained frozen until the events of "The Avengers" decades later.
Marcus, however, revealed that "a large chunk of the third act was Cap fighting this robot" known as the Panzermax. Much like how the classic first-person shooter game "Wolfenstein" ended with the player fighting a robot controlled by Adolf Hitler, "Captain America" saw the eponymous hero facing off against Red Skull in a very similar contraption.
It's unknown how Cap's fight with the Panzermax would have played out, but it presumably would have ended in a victory for the star-spangled hero. Then, things likely would have played out much the same as they did in the final movie. Red Skull is sent to Vormir, and Cap crashes the plane into the ice, paving the way for MCU films to come.