You're wrong about River. River's not on the ship. They didn't want her here, but she couldn't make herself leave. So she melted... Melted away. They didn't know she could do that, but she did.
River ,'Objects In Space'
Buffista Music 1: The Music (And Who Can Blame It) Swells
There's a lady plays her fav'rite records On the jukebox ev'ry day. All day long she plays the same old songs, And she believes the things that they say.
She sings along with all the saddest songs, And she believes the stories are real. She let's the music dictate the way that she feels.