> I've seen comment citations in the past. I still can't figure out how to get those to work.

Like this? It's just italics and a > symbol.

Nope, like wiki style citations to external links. Maybe it's just some superscript trickery, but I've seen it from multiple people, so I assumed it's a hidden feature.

I think it's Unicode superscript characters¹. Does that look like what you've seen?

1: https://en.wikipedia.org/wiki/Unicode_subscripts_and_supersc...