This episode makes many references to Elton John. In reality, Elton John himself is a fan of the show, and he was delighted to be included in this episode.
First episode to not feature Eve.
After telling Villanelle about the Flat Earth/Fake Moon Landing theory. Fyodor tells her about a world-wide conspiracy theory of his. He describes a shadow organization that is composed of intelligence agents from various countries and works to secretly control world policy. This actually describes Villanelle's employers (the Twelve) very accurately.
Jodie Comer is the only one of the regulars of the series to appear in this episode.
The song heard during the last sequence of this episode is a Godspell titled "Spriritual" by french rock group Magma. The leader of this group, Christian Vander, made up their own language for their lyrics: Kobaïan. His voice can be heard in this tune singing in kobaïan.