Something I have not seen people say. I have seen people comment about how did River know to kill the silence since she could not see it, they talked about she saw her dad scared….
But before that, River said “My old man didn’t see that did he? He get’s ever so cross”, before we assumed it was the Doctor, but old man usually refers to dad, River is possibly talking to her dad, trying to give him a hint or the Doctor a hint.
Doctor Who for You 