The Third Doctor previously faced giant spiders in the season 11 final story "Planet of the Spiders".
Planet of the Spiders: Part One (1974) through Planet of the Spiders: Part Six (1974).
The title is most likely a play on words of the infamous Sex Pistols' song "Anarchy in the UK".
The Doctor says 'dude' and is excited about using that word. Previously the Twelfth Doctor got a medieval audience to say 'dude' in The Magician's Apprentice (2015).
All of the exterior hotel shots and some of the interior where shot at the Celtic Manor hotel, near Newport, Wales.
This story shares similarities with two different Third Doctor stories: Planet of the Spiders (the Third Doctor's final story, in which he faced the Spider Queen of Metabellis III) and The Green Death (final story of companion Jo Grant, which featured mutated, giant maggots in a Welsh mine). Oddly, despite expectations, no reference is made to either of these stories.