'''WARNING! THERE MAY BE UNMARKED SPOILERS!'''
* DoNotDoThisCoolThing: Behind the Scenes example: Creator/MattSmith relates that he and Creator/JennaColeman were told not to swing on the bars during the TARDIS's fall to Trenzalore. So what does Matt Smith go and do? Swing on the bars during the TARDIS's fall to Trenzalore.
* HilariousInHindsight: The [[Recap/DoctorWho2015CSTheHusbandsOfRiverSong 2015 Christmas special]] revealed that by the time of her death in the Library, River had not only already met the Twelfth Doctor, but ''he'' was the one who truly returned her love for him, staying with her for twenty-four years on Darillium. It is therefore very possible that, despite not letting on, she already knows at least something of Clara's future. This adds extra humour to her realization that the Doctor had given Clara the impression that River was a man!
* IKnewIt: A few fans successfully guessed the revelation regarding Clara: that the modern London Clara is the original and somehow ends up splintered across time to save the Doctor's life countless times.
* TheyWastedAPerfectlyGoodCharacter: The Whispermen have an incredibly creepy design (with, as mentioned, a very Slender Man-esque vibe) and a fairly menacing presence in the first half of the episode, complete with an IronicNurseryRhyme in the associated minisode. Too bad they end up being little more than disposable spare bodies for [[ArcVillain the Great Intelligence]].
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