This is often cited as one of the most dark, grim and violent Doctor Who stories, with a body count of 59 people killed on screen, which is much higher than The Terminator (1984), a violent sci-fi movie released later in the same year.
Matthew Robinson was surprised that the aspect of the story that the BBC received the most complaints about was not the graphic violence of the serial, but rather that one of the prison crew is seen to be smoking a cigarette early in the first episode.
This story was intended to be four parts of the usual 25-minute length. However, due to the BBC's coverage of the 1984 Winter Olympics held in Sarajevo, Yugoslavia, the series' regular slot was not available. Rather than interrupt transmission, the decision was taken to transmit the story as two double-length episodes (45 minutes per episode), on consecutive Wednesdays rather than season 21's normal Thursday/Friday timeslot. It is often asserted that it was directly because of the success of the two-part experiment that the following season was produced in the same format: however, this decision had already been taken.
The debut of Terry Molloy as Davros, who had worked before for Matthew Robinson. Robinson cast him because he wanted a talented voice artist who was also prepared to endure hours in make-up and perform through a mask. Molloy was unfamiliar with the character of Davros, not having watched the series since the Patrick Troughton era, so he watched the tape of Michael Wisher in the serial Genesis of the Daleks: Part One (1975) as his preparation for the role.