Whilst deciding which of the seven chairs - six of which are deadly, while one remains safe - to choose, the King of Hearts recites a version of the children's counting rhyme "Eeny, meeny, miny, moe" (used to select a person to be "it" for games and similar purposes), which includes the racial slur "nigger" in the second line. The use of this word was still considered acceptable by the BBC at the time of the story's original 1966 broadcast. Although the rhyme is still present on BBC Audio's CD release of the story, it has been censored on the CD release by placing part of Peter Purves's narration over the top, in order to correspond to modern views on the use of this word.
William Hartnell was on holiday during filming. Pre-recordings of his voice were heard and Albert Ward was a hand double for scenes where the mostly invisible Doctor played the Trilogic Game throughout the story.
This episode was wiped by the BBC and no copy of it is known to exist.
This episode was watched by 8 million viewers on its original transmission.