Apology cue cards

Due to his sometimes colder and often absent minded traits the Twelfth Doctor started using apology cue cards to get himself out of tight situations. In the Drum, Clara Oswald prompted the Doctor to use the cards to respond appropriately to the death of Jonathan Moran, who was the crew's friend, after the Doctor being excited about the apparent "proper" existence of ghosts in the Drum.

Some of the apologies on the cards included: "I completely understand why it was difficult not to get captured"; "It was my fault, I should have known you didn't live in Aberdeen"; "I didn't mean to imply that I don't care"; "No-one is going to be eaten/vapourised/exterminated/upgraded/mortally wounded[/]turned to jelly[.] We'll all get out of this unharmed"; and "I'm very sorry for your loss. I'll do all I can to solve the death of your friend/family member/pet." (TV: Under the Lake)

Behind the scenes
The Aberdeen cue card is a reference to the episode School Reunion, in which Sarah Jane Smith is revealed to have been mistakenly dropped off there (instead of in Croydon) by the Fourth Doctor.