Re: Why no cloister bell in pandorica opens / big bang?
Maybe only the Doctor can hear it. In the critical moments River is the only one in the TARDIS.
I think the more important thing is, why did River go through the whole Charade of going to Amy's house and looking at all the Roman stuff, when she knew full well Rory was her Dad, and had already seen him dressed as the Centurion?
I'm being extremely clever up here and there's no one to stand around looking impressed, what's the point in having you all? - The Doctor, interrupting a very important conversation.