The very striking abandoned factory used throughout season one happens to be Welwyn Garden City's derelict Shredded Wheat factory. The factory was built in the 1920s and manufactured the breakfast cereal until 2008. A listed building, it is set to be converted into housing in the near future. The town also provided many of the locations for Pegg's 2013 sci-fi feature "The World's End".
This is the second TV-show collaboration between best friends Nick Frost and Simon Pegg after the TV show 'Spaced.' They have starred in 6 films together.
In 'The Revenge Of The Chichester Widow', where Gus encounters the doll in the basement, there is an insignia on the wall in a circular shape. This is a mark called Aegishjalmur, also known as the Helm of Awe and Terror. The overall meaning of this word might be the protection in the front. In fact, many Viking warriors once applied this symbol in their forehead and between their eyebrows for protection and victory.
On 11 February 2021, Nick Frost announced on Instagram that the series had not been renewed for a second season.
The character Dr. Peter Toynbee is mostly like a nod to Arnold Toynbee, author of the book 'Experiences', which contains a passage about bodies and souls and resurrections, a major plot point in the series. The passage is also referenced in the Toynbee Tiles, a series of mysterious tiles with messages about the 'resurrection of the dead on Jupiter'. Arnold Toynbee is directly mentioned in the tiles, hence the name. The tiles have been discovered embedded into the asphalt in several U.S. and South American cities since the '90s.