The breadcrumbs for future stories have been laid out by River Song throughout her numerous appearances and keen fans would have noted that the crash of the starship Byzantium at the start of The Time of Angels sounded familiar because River mentioned it to Tenth Doctor way back in Series 4's Silence in the Library/Forest of the Dead in 2008. That two-parter, of course, was written by Steven Moffat himself. At that point River assumed the Tenth Doctor was an older incarnation, though there is evidence in Series 5 to suggest that she met him more than once. In The Pandorica Opens, River appeared as the Egyptian queen Cleopatra and in Series 2 The Girl in the Fireplace (another Moffat episode), the Tenth Doctor mentioned a relationship with the Cleopatra. Was that River Song or the real Egyptian Queen? If it was the former then it suggests that she never revealed her true identity, which would've been so unlike her! The Weeping Angels two parter is also infamous for two other reasons. During its original 2010 broadcast there was public uproar when an animated Graham Norton popped up during the final cliffhanger moment of The Time of Angels. There was also the suggestion of a huge continuity error when a jacket-less Doctor confronted Amy in Flesh and Stone. As it turns out though, it was all part of a bigger story plan, revealed in The Big Bang, involving the Doctor jumping back through his own timeline. Sneaky!