Name your top scenes from the Marvel Cinematic Universe, and there are a few flawless moments that will probably make the list. Captain America and Iron Man's fight in Siberia in "Captain America: Civil War" is a top option. So is Thor's arrival on the battlefields of Wakanda in "Infinity War." If there's one moment in all of the on-screen Marvel magic that always gets fans worked up into a collective ball of nostalgic emotion, though, it has to be the famous "Portals" scene at the end of "Avengers: Endgame."

Steve Rogers is standing amidst the ruins of the Avengers compound: beaten down, desperate, and at the end of the line. Yes, he can do this all day, but night seems to be approaching. Then, seemingly out of thin air, he hears the voice of Sam Wilson. "On your left," the future Cap says — a callback to the...