The three shots of the Doctor walking through Paris, was the first instance of location filming for Doctor Who (1963). The location filming actually took place at Denham and Gerrards Cross in Buckinghamshire. In these shots, Brian Proudfoot had to double for William Hartnell as the Doctor.
This episode survives only as a 16mm tele-recording.
Brian Proudfoot attended the studio recording so he could shadow William Hartnell to study his movements and walk so he could double for him in the location shoot. According to Carole Ann Ford, this annoyed the actor immensely.
Ian only appears in a pre-filmed insert in order to give William Russell a holiday during production.
The first use of an establishing on-screen caption in Doctor Who (1963) is featured in this episode: the word "PARIS" is superimposed over a piece of artwork showing the French capital.