I have a question about the finale.
They walked all over the planet, they walked on water to get places and didn't sink in. Yet when they drank their wine the wine moved. How did that work?
Chronitons are lighter than air, so they floated upward, flowing around the objects Fry and Leela interacted with, but not sinking down to affect things below their feet.
(Just read it in the Professor's voice, and it'll work.)