William Hartnell was injured during filming (he was dropped while being carried down from the Dalek saucer). His injury was sufficiently bad that he was not available to film the following week's episode. He appeared only as a brief reprise from this episode and then voiced over Edmond Warwick (who collapsed a short while into the episode).
Whilst Doctor Who had featured Location filming the the 1st season story 'The Reign of Terror' this is the story that made it popular because of the extensive location work done around London.
Edmund Wawrick who doubles for an Injured William Hartnell previously appeared in the Third Entry of the Season 1 story "The Keys of Marinus" which Hartnell was also Absent from (Though there he was on Holiday), it was noticed during that studio session that he bore a resemblance to the leading man, and was remembered and doubled for him here.
the two would then share the role of the Doctor and meet face to face in the 5th entry of the subsequent Dalek Story "The Chase", where Warwick was the Robot Doctor in long shots, and painfully noticeable in many close ups.
the two would then share the role of the Doctor and meet face to face in the 5th entry of the subsequent Dalek Story "The Chase", where Warwick was the Robot Doctor in long shots, and painfully noticeable in many close ups.
This episode was watched by 11.9 million viewers on its original transmission.
This episode takes place in London in the 2160s.