Doctor Who: 20 Things You Didn't Know About Heaven Sent
2. What Happened On The First Few Cycles?
When we first see the Doctor stuck inside the confession dial, he's already been there for a long time.
So, what was he up to when the cameras weren't rolling? What happened on the very first cycle, and who left the clues leading the Doctor to Room 12? Steven Moffat has the answers.
In Doctor Who Magazine's production notes, Moffat said that the Doctor was "ancient" by the time he'd first worked out how to escape the castle. That means he was a very, very old man when he first started punching the wall.
Furthermore, another ancient version of the Doctor never punched the wall at all. This Doctor - realising that future versions of himself would need to find Room 12 much quicker - scratched "I Am In 12" in as many places as he could, and hoped that some of these messages survived the castle's reset.
This version of the Doctor also wrote "I Am In 12" on the back of Clara's portrait, and this too survived the reset. But in Moffat's own words, "the Doctor draws too much strength from her smile ever to turn her face to the wall."
Just when you thought this episode couldn't get any sadder.