WARNING! THERE MAY BE UNMARKED SPOILERS!
Fridge Brilliance
- The Doctor is convinced that he may be constantly followed by a being who cannot be seen. He is; The Great Intelligence.
- Aside from the Great Intelligence, The Silence has already been established as a foe that might be in your presence at any moment without you having any recollection of it. The end result would be effectively the same as if you'd never been aware of them. At least the Doctor knows about them, and they can be caught in the act.
- The episode even presents a reason for why someone or something may be doing its best to avoid being encountered by you: It could be a time traveling you from the future.
- Watch "Heaven Sent", then go back and watch the opening monologue of "Listen". Did the missing chalk actually happen in the real TARDIS, or did it happen in the Doctor's Mental World as an expression of his theorizing about "perfect hiders"?
- Danny's extreme reaction to Clara's idle quip about killing Courtney makes a lot more sense after seeing "Dark Water" / "Death In Heaven".
