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'
Natter 25: Half the Ways to Leave Your Lover
Off-topic discussion. Wanna talk about corsets, duct tape, or physics? This is the place. This is also a world- wide Spoiler-Free Zone. Please don't discuss what's aired this season; use the show discussion threads for that.