Number 6's observation that "I'm new here" has led many fans to believe that this is meant to be among the series' earlier episodes.
An unfilmed scene, involved a freshly dug grave, where the doctor (played by Duncan Macrae) would bury a body, on which he had conducted gruesome experiments, and the burial was to be observed by No 6.
The title refers to 'The Danse Macabre' by Camille Saint-Saëns, written in 1874.
Trevor Howard was to play No 2 in this episode, but was unavailable. No 2 was originally supposed to be dressed as Jack the Ripper for the carnival sequence, but when Mary Morris took on the role, this was changed to Peter Pan, whom Mary Morris had played in a pantomime at the Savoy Theatre in London. In fact, Peter Pan is traditionally played on stage by a young woman.
No 6 is given a show trial by three judges and no jury. This is, as he points out, the same system used during Robespierre's Reign of Terror, during the French Revolution.