The Crawling Terror
Roots: Giant insect B-movies. Clearfield's half-mask recalls the stage version of The Phantom of the Opera, as Kevin notes. The village of Wyndham is possibly a reference to John Wyndham. There are references to Call the Midwife, Godzilla, Shaun the Sheep, Range Rovers, Rolls Royce, Star Wars (the Millennium Falcon), Fiat, Volkswagen Beetles, Harry Potter, Mimic, Josef Mengele, Hammer Horror, Turing, Welchman, Knox, Aleister Crowley, Winston Churchill, Indiana Jones and the Last Crusade, The Great Escape, Aliens, The Wicker Man, The Wolfman, both versions of Clash of the Titans, Ray Harryhausen, and Raiders of the Last Ark.
Continuity: The Wyrresters are a mutant arachnid species from the planet Typholchaktas in the Furey-King Maelstrom. They resemble giant scorpions.
The Doctor carries a piece of chalk in his pocket. He doesn't know whether or not he knows how to ride a motorbike in his new body. He poses as Doctor McGuinness from St Andrew's University. He knows of the Wyrresters.
Clara was stung by a wasp when she was a little girl. She carries a hairpin. Jenny Flint taught her how to pick locks. Her mind is temporarily swapped with that of the Wyrrester Gebbron, leaving her in its body non Typholchaktas.
All UNIT troops are currently engaged in a crisis in the Canary Islands, where robots with spiked heads are emerging from the recently erupted El Hierro volcano [possibly Quarks - this may be a reference to the DWM comic strip The Fires Down Below].
Links: Clara thinks about Danny Pink (Into the Dalek). The Doctor checks to see if there is a trapped spacecraft hovering in the hyperspatial dimension above the stone circle (The Stones of Blood). Dr Judson is mentioned (The Curse of Fenric). Department C19 is mentioned (Time-Flight).
Location: Ringstone, Wiltshire, England,  and 21st March 1944; Typholchaktas, .
Unrecorded Adventures: The Doctor performed a tambourine solo at Woodstock. he fixed the central-heating boiler at Cowbridge House at Malmesbury in winter 1939.
The Bottom Line: A story so derivative of other stories involving giant insects and stone circles, that it actually starts name-checking films it rips-off, whilst throwing in a reference to The Stones of Blood. It's workmanlike at best and the Wyrresters aren't original enough to be really interesting, although Tucker captures both the Twelfth Doctor and Clara reasonably well. At least Clearfield is a three-dimensional villain. Competent, but dull.