The Doctor Falls the episode, the Doctor (Peter Capaldi) must save himself and the remaining human population of a gigantic colony ship from Mondas, while also dealing with two different incarnations of the Master (Michelle Gomez and John Simm) at once. The episode features a cameo from the First Doctor, now portrayed by David Bradley. He had previously played William Hartnell, the original First Doctor actor, in the 2013 "Doctor Who" docudrama "An Adventure in Space and Time". Aboard the colony ship reversing from the event horizon of a black hole, the Doctor finds Bill has been converted into a Cyberman. The Master
An Adventure in Space and Time of 1960s Dalek props crossing the bridge, in a recreation of a famous scene from "The Dalek Invasion of Earth" (1964). Interior scenes replicating early "Doctor Who" production at Lime Grove Studios were also filmed, with replicas of early television equipment being used. A number of the cast have appeared in "Doctor Who" at one time or another, most notably original companions William Russell and Carole Ann Ford. David Bradley appeared in the Series 7 episode "Dinosaurs on a Spaceship", while Jessica Raine was in the Series 7 episode "Hide" and the "Call the Midwife" charity cross-over mini-episode; Jeff Rawle