Doctor Who: 20 Things You Didn't Know About Heaven Sent
8. Many Shots Were Filmed Many Times
Rachel Talalay did a damn fine job on this episode, especially considering how much stress she was under.
The director had to get this incredibly tricky episode spot on, all the while having Moffat in her ear telling her to do things she'd already done!
Talalay was instructed to record the same shots multiple times, but slightly differently. This was so they could be used in scenes showing later iterations of the Doctor's journey to Room 12.
Why did they have to be different? Well, because each trip around the castle was different! This made each of the rapid-fire cycles at the end of the episode feel slightly distinct, as they probably would be.