Doctor Who: 20 Things You Didn't Know About Heaven Sent
17. Those Are Actually Peter Capaldiās Skulls
How many times has the Doctor died in a single episode of Doctor Who?
Heaven Sent has to hold that record, as the Time Lord spends four-and-a-half billion years getting repeatedly bumped off by a bloke in a bedsheet.
As a result, the castle the Doctor is trapped in is littered with various copies of his own skull, and that statement is actually more true than you might think.
That's because Peter Capaldi's own head was used as the model for those skulls. It was taken from a life-sized cast made of the actor for the Ghost Doctor in Under the Lake/Before the Flood.
Don't ever say Doctor Who doesn't take small details seriously.