This part of this story is the only place within the series original run and the new (2005) run to feature the Doctor's real name. It was, previous to this, deemed as unpronounceable by humans, and, after this, never brought up again. In the new series, the Doctor does remember his name, but chooses not to give it as a memento of the dead Time Lord race, but, in this story, The Doctor runs into an old school chum who reveals his name to be Theta Sigma. However, in "The Happiness Patrol", this is said to be a college nickname.
Bob Baker and Dave Martin originally created Drax for an earlier draft for The Hand of Fear. The character was originally an elderly eccentric along the lines of the aged prisoner in the novel The Count Of Monte Cristo.
Twenty-three minutes into transmission of part five, a technical fault on the playback equipment - which occurred at the point where the Doctor is being escorted to the TARDIS by the Mute and the Shadow makes to remove his control device from Princess Astra, saying "Now, Princess, your work is done. Your dest-" - resulted in the programme going off the air for twenty seconds. BBC continuity apologised to viewers for the breakdown in transmission, displaying a TEMPORARY FAULT caption slide and playing music, "Gotcha" by Tom Scott (better known as the theme music to Starsky and Hutch (1975)), until the fault was rectified. When transmission was restarted, the 625 line PAL colour videotape had been slightly rewound so that there was a repeat of the action immediately prior to the break, with the Shadow's line finally completed as "Your destiny is at hand."
This episode was watched by 8.6 million viewers on its original transmission.