You said this much funnier than I did (and with pictures!) but. OMG, I AGREE. Just.. it was totally an orgy of continuity and hints that got MADE CANON and made my brain go happy-splody EVERYWHERE. I forget how much I know about this series until they do an episode like this, and then I go to my happy place repeatedly because... OMG.

IT FITS LIKE A PUZZLE. A PUZZLE OF AWESOME.