Captain America knew something was off thanks to a baseball game that was broadcasted on the radio when he woke up after being frozen for decades, and this detail has sparked a lot of questions about S.H.I.E.L.D. and Nick Fury’s attention to detail, but a theory fixes this plot hole by connecting it to Captain America: The First Avenger.
The first Captain America movie told the origin story of Steve Rogers, from his days as a fragile young man looking to the army to taking part in Project Rebirth and becoming Captain America after being injected with the original Super Soldier Serum. At the end of The First Avenger, Captain America had to crash his plane in the Arctic to avoid detonating the weapons it carried, and while he was presumed dead, he actually spent almost 70 years frozen. The final scene in The First Avenger saw Captain America awakening in a 1940s-styled hospital room and escaping only to find himself in present-day New York City, where he was approached by Nick Fury (Samuel L. Jackson), who told him the truth.
What made Captain America suspicious of his surroundings was a radio broadcast of a baseball game from 1941, a game he actually attended. S.H.I.E.L.D. went to lengths to create a 1940s environment in order to ease Rogers into what was now happening, so it’s strange that they made a mistake with the game they chose to broadcast. This plot hole has made way for different theories on what really happened there and why it was most likely intentional, and among those is one that links Fury’s “mistake” at the end of Captain America: The First Avenger to Captain Marvel, as this could have been a way to test if this was the real Steve Rogers or if he was a Skrull.
Fury and his crew making a mistake like broadcasting the wrong game in Steve Rogers’ room has been pointed out as a plot hole as they paid attention to even the smallest details, so it doesn’t make much sense that they blew it all with the wrong broadcast. Captain Marvel introduced Skrulls in the MCU, whose shapeshifting abilities allow them to pose as humans seamlessly, and they can even replicate the recent memories of the person they have simmed. By broadcasting the wrong baseball game, Fury could have been testing Steve Rogers: if he noticed the mistake, it meant he was the real one, if he didn’t, then it was a Skrull posing as Captain America.
It’s unlikely Skrulls were already in the MCU’s plans when Captain America: The First Avenger was in production, but the MCU has already retconned many details from past movies, such as confirming that the kid wearing an Iron Man mask in Iron Man 2 was Peter Parker, so it wouldn’t be surprising if, at some point, Secret Invasion, it will surely be revealed that they posed as some important characters at some point in the MCU's history, and it’s not outside the realm of possibility that this particular theory could be confirmed or debunked.
