When The League of Gentlemen was sold to Korea the broadcaster there renamed it Psychoville. Psychoville was just supposed to be a working title for this project - however the name stuck.
The involvement of Pemberton and Shearsmith's The League of Gentlemen co-star Mark Gatiss in Episode 4 of the show was kept a secret from viewers, so it was a shock for many when he appeared at the door.
The press were asked not to mention the star's involvement in the show in any previews, and Gatiss was credited under the anagram 'Sam Kisgart' in the listings magazines.
The character of Tealeaf was originally supposed to have a Yorkshire accent, but as actor Daniel Kaluuya jokes: "as soon as they heard me trying to put on the accent, they told me not to do it again."
Episode Four is special in that it is a homage to Alfred Hitchcock's Rope (which features very long scenes without cuts). Shearsmith, Pemberton and the Psychoville production team wanted to take this idea to the limit and do their episode in as few cuts as possible. As a result, the cast and crew spent almost two days rehearsing the episode, and then two more days to film. They finally got everything right on the 16th take on the 2nd day.
The final episode is actually made up of just two takes (with an un-noticeable wipe at 19 minutes, as the chest is opened)... however this two scene compromise was only because the HD camera equipment the production was using had to be powered down every 22 minutes (so it didn't overheat) and thus the full 30 minutes in one go was not possible.
The DVD of the series features a behind-the-scenes shot revealing how the camera moved around the set. A whole team of stage hands were used to silently slide furniture out the way of the camera dolly as it zoomed in, and then back into position as the dolly moved out again.
The fact there were no camera cuts in Episode 4 meant that some things that would normally be quite easy to stage became quite a challenge.
For example, the script required the dead body hung on the back of the door to be stabbed with a knife as the door opened. This was achieved via a little door in the back of the set.
Reece Shearsmith explains: "A half magnetic knife had to be attached in the instant the body swung round. Being a bit of a magician, it was actually me who came up with the solution to use a magnet to attach the knife that goes into the body. It was a mad scramble to apply the blood to the coat before the door was closed."
Lorna, the girl whose hair Mr Jelly was combing at the party in Episode 1, is Reece Shearsmith daughter Holly in real life.
The song which David and Maureen dance to in episode four is "Superman" by Black Lace.