1)"Once upon a time - the end. Dad skills."
2)"Dan the Soldier Man".
3)"Sontarans perverting the course of human history." _ A callback to "Robot", which makes it seem like the events of "The TIme Warrior" have haunted the Doctor for thousands of years!
4)Nice touch, tying back the "The Day of the Doctor".
5)I also liked the idea that Clara ends up being the creature under the Doctor's bed!
Overall: I quite liked this story, one of Moffat's better efforts, I thought It is funny, though - in-story, at least, Clara has become of the most important people in the Doctor's life! Because of her moving up and down his timeline, she's become as integral to his life, as he has to the life of the universe!
I'm more than a little ambivalent about Clara's seemingly unending influence over the Doctor's history.
I did like the ambiguity of this story. I went in assuming that this was going to be another Moffat "let's creep you out" monster stories. Shadows, then statues, now "the thing under the bed." But ... maybe there was no monster, and if there was it didn't really matter. That wasn't the point of the story.
Moffat is really using this season to explore different ideas about herioism, and what type of hero the Doctor is (and how he feels about it).
Didn't Donna call Ten a "stick insect" once?