*Spoilers*
They may also reference Chrono Trigger. Iron Man starts talking in Shakespearean language in the forest when he fights Thor, this on top of the fact that the characters have a few combined moves throughout the movie, along with the fact that I think the first combination is technically when he fights Thor and Thor accidently charges up Iron Man with a move that includes electricity, and having someone play Galaga, makes me think this, but I'm not as sure as the Zelda reference, but also, the Zelda reference in itself helps to support this.
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