The Doctor and Peri engage in a William Shakespearean word duel. He says "Cowards die many times before their deaths. The valiant never taste of death but once." This is a verbatim quote from the title character of Julius Caesar, Act 2, Scene 2. She replies "Discretion is the better part of valour." This is the popular paraphrase of "The better part of valour is discretion," spoken by Falstaff in Henry IV Part 1, Act 5, Scene 4.
This was the last Doctor Who episode to be directed by a woman until Blink (2007) over 20 years later.
This episode was watched by 7.3 million viewers on its original transmission.