6. Why Didn't River Recognise That Ten Was Younger Than Eleven?
On the subject of 'Silence in the Library', River's supposed to have pictures of all the Doctor's faces, but when he first met her, she didn't realise that this was a younger incarnation of the Doctor. What's more, she asks if they've done "The Crash of the Byzantium" yet; how could they have? He hadn't regenerated yet. It's possible that River thought that she was talking to Twelve, and of course, they always meet in the wrong order. But going by facts already established in the show, a Time Lord can recognise another Time Lord regardless of their face; the Doctor did so when he knew that Professor Yana was really the Master in disguise. Yes, River's only half Time Lord, but when she looks into Ten's eyes, she realises how young he is. Not only is this lovely that River can see the 900-year-old beyond the 40-year-old Scottish actor, but it's an insight into how Time Lord driving licenses are checked. Alternately, Moffat could have intended to write another adventure with River and Ten: we'll never know. Well, until November 23rd of course.