Neil Cross wanted to write "a really old-fashioned scary episode of Doctor Who targeted especially at children nine to twelve, which was how he remembered Doctor Who (1963) at that age. He stated that "time travel and ghosts are echoes of one another. What is a ghost, if not a fragment caught in time?" He aimed to show suspense and tension, as he felt it was more terrifying than "full-on shock horror blood and gore".
The Doctor visited Metabilis 3 and had fun with blue crystals in Planet of the Spiders: Part One (1974).
The spacesuit The Eleventh Doctor wears was worn by The Tenth Doctor in The Impossible Planet (2006), The Satan Pit (2006), 42 (2007), and The Waters of Mars (2009).
This was the first episode filmed by Jenna Coleman as a series regular, but screened as the fourth episode in series 7b.
The Crooked Man's movements were done in reverse and then played forward, to give it an unnatural movement.