10 Doctor Who Secrets That Were Hiding In Plain Sight
6. The Doctor's Speech Is Written On The Wall (Heaven Sent)
Heaven Sent is topped and tailed with two great Peter Capaldi speeches, and the first one can also be glimpsed in a blink-and-you'll-miss-it shot on the walls of the castle.
At first glance, it appears as if someone at the locations used to film the episode forgot to obscure some tourist text. But on closer inspection, it's clear that this is in fact the Twelfth Doctor's opening monologue about death, and not some obscure information about Welsh castles.
A deleted scene would've apparently shown the Doctor reading this speech from the wall, but this was changed so that it became an opening monologue instead. And considering how effective that opening is, this was no doubt the right move – not to mention that the Doctor standing there reading from a wall wouldn't have been the most riveting scene, despite how incredible Peter Capaldi is as an actor.
This can also be interpreted as the Doctor's confession dial decorating the castle with sombre speeches and sentiments, in an effort to wear the Doctor down.
Although, from an interior design standpoint, I'd take "You begin your life, and it begins a journey towards you", over "Live, Laugh, Love" any day of the week.