DOCTOR: So where are we now, Doctor Song? How's prison?

RIVER: Oh, I was pardoned ages ago. And it's Professor Song to you.

DOCTOR: Pardoned?

RIVER: Mmm. Turns out the person I killed never existed in the first place. Apparently, there's no record of him. It's almost as if someone's gone around deleting himself from every database in the universe.

DOCTOR: You said I got too big.

RIVER: And now no one's ever heard of you. Didn't you used to be somebody?

DOCTOR: Weren't you the woman who killed the Doctor?

RIVER: Doctor who?