Trivia: For a show with a "Circus and Clowns" theme, it is appropriate that this Doctor Who story was filmed in a tent. It wasn't planned that way, but the studio at BBC TV Centre in London that was originally to be used for filming "The Greatest Show in the Galaxy" had to be closed at short notice when the presence of dangerous white asbestos was discovered in the studio's structure. With no alternative studios available, filming was switched to a marquee temporarily erected in the car park of the BBC Studios at Elstree.
Trivia: Many people have commented on how similar the Kandy Man was to the Bertie Bassett character used to promote Bassett's Liquorice Allsorts. One of those people was the chairman of Bassett's, who wrote to the producer of Doctor Who to complain that his company's trademark had been infringed. The BBC Copyright Department replied that they believed that no infringement had occurred, although they did promise that the character would not be used again in the future.
Trivia: This story is set weeks after the time frame in which the very first Doctor Who episode, "An Unearthly Child", took place. There is a scene in a house, with a TV in the corner, where the continuity announcer begins to announce the start of a new Saturday early evening science fiction story - it is the announcement which launched Doctor Who - which cuts out just before the title is mentioned.Jeff Walker