I thought it interesting that Mr Universe got buried together with Shepherd Book and Wash. Mr Universe's dalliance with the crew of Serenity was all too brief, but nonetheless there he is, honoured by being laid to rest alongside her fallen crew.

Another thought. River's talent could stem from two sources: her own innate talents, and also her long term exposure to the minds of other skilled people. No wonder she knew how to fly the ship, after all those long voyages in the company of Wash, absorbing his experience by osmosis. She could very likely also be perfectly capable of performing the tasks of a ship's doctor, a Captain ... even a Companion.