#besides if he was wearing slippers the whole time

A small, pointless Sans theory:

Have you ever noticed how we can’t actually see his slippers in his overworld sprite?

We know from official art and merchandise (and Smash Bros) that they’re pink, so why is there no pink on his actual sprite? In all likelihood it’s a simple oversight, or they only decided they would be pink after the game’s release (like Kirby!) but we can go deeper.

Take a moment to think about when we get to see that he’s even wearing slippers: his boss fight. A fight that takes place at arguably his lowest point; not a single person you’ve encountered has been spared, and he seems aware of the possibility of the world itself ending if you get past him.

And where exactly has he been the whole run? He might be following you around more stealthily than usual, but in this scenario it’s not hard to imagine that he’d spend a lot of time in his room.

His house.

Where you would expect someone to be wearing slippers.

I find it completely believable that he would teleport straight from his house to the final corridor without bothering to switch shoes first - this is Sans we’re talking about, after all. But that still leaves the question: what’s he wearing in his overworld sprite, then?

The funniest option is that he’s not wearing any shoes. Just walks around in the snow barefoot all day like a champ

But as far as actual alternatives, there are exactly two instances I could find of Official Sans Material in which he wears sneakers instead:

Granted, these shoes aren’t completely white like his overworld sprite, but they do have white tips, and I think including a dark color (like the one on the plush) on his sprite would confuse where his pants end and shoes begin.

And here’s the real kicker: the plush is actually smaller than the version that wears slippers. Just like how his in-game sprite without the slippers is smaller than the one with them. Coincidence?? Quite possibly, but it’s fun to think about.