Since Super Mario Bros. 2 takes place in a dream world, perhaps there’s something in the fact that Mario and his companions begin the adventure by falling down a dark, vertical passage, like Alice in the rabbit hole.
You could perhaps also say that Subspace is similar to the looking-glass world, but the main Alice reference in the series is the idea that a magic mushroom will make Mario grow in size. In fact, New Super Mario Bros. adds mushrooms that can make Mario giant or tiny. The similarity to the Caterpillar’s mushroom is almost certainly not coincidental. And yes, it was probably a drug reference in the first place, driven home even more by the fact that the Caterpillar smoked a hookah.
Not that this necessarily means Lewis Carroll himself did hallucinogenic drugs, although I suppose we’ll never know for sure.
I’ve mentioned some aspects of SMB2’s dream theme before, and the ending suggests that the entire game took place in Mario’s dream. (Strange that, in his own dream, his brother and friends are much more useful than he is.)
Does this mean the game never actually took place in general Mario continuity? It’s hard to say. Some of the enemies introduced in this game reappear in others, and how is that possible if they’re just dreams? In fact, Shyguys show up quite often in Yoshi’s Island, and that’s a prequel to the other games. Maybe the monsters who tried to destroy Mario when he was a baby have become symbols of fear to him, and hence appear in his dreams. If so, they’re not very effective symbols of fear, as all they do is walk forwards.
Well, except for the ones on Autobombs. It’s typical for the people you meet in your dreams to have the appearance of people you’ve met in real life, right? Perhaps that applies to weird beings from the Mushroom Kingdom as well. Still, it must be pretty surreal to see a creature you first encountered in a dream to show up to play sports with you.
Some of the inhabitants of Subcon, including Wart himself, have yet to reappear in waking-world Mario games, but I have to say I still like the idea of their being real. Mind you, I grew up on the Super Mario Bros. Super Show, and the cartoons brought in pretty much all of the SMB2 enemies, and they didn’t take place in dreams (at least as far as we know). Did Wart perhaps transport real creatures into the dream world, or vice versa? I suppose we’ll never know for sure.