Central Premise Recycled From: The Stone Tape.
Moffat Autorecycling: Alien that 's Not Bad, Just Misunderstood. Girl caught in timey-wimey phenomenon, people living at different speeds, “everybody lives!” type ending, Scottishness.
Recycling Other People: Multiple references to Quatermass, for reasons to be detailed below. Sapphire and Steel, that episode of Sarah Jane Adventures which also rips off The Stone Tape, The Omega Factor (creepy psychic phenomena in Scotland). “Battlefield” (chalk circle). The Haunting. “The End of the World”. “Planet of the Spiders” (well, not much, but that damned Metebelis Crystal has had so much press it has to be mentioned). That bit in “The Robots of Death” where the Doctor explains a complicated space-time phenomenon using a pair of boxes of different sizes, as here where he explains pocket universes using a pair of balloons of different colours. “The Parting of the Ways”.
Evil Household Objects: Just the usual psychic-phenomena stuff like candles that blow out, temperatures that drop, and so on.
Doctor Who!: Sort of: “Doctor What?” “If you like”
Outfits!: The Doctor just had to remind us that “The Satan Pit” exists, didn't he?
Small Child!: Mercifully, no.
Murray Gold's Top Ten: Shrilling minor-key horror-film incidentals this week.
Clara Dies Due To: Nothing, but she does get to see her own doppelganger.
Clara's Job of the Week: Holder of candelabras.
“Run, you clever boy, and remember”: Again, no.
Topical Reference to Puzzle Future Generations: Ghostbusters, possibly.
Continuity Frakup of the Week: Others have pointed it out, but it's worth repeating that Professor Palmer is way too young for his backstory; the actor is 49, meaning he'd've been 19 in 1944, making him rather young for covert ops. The explanation is allegedly that the writer had wanted to make the character Professor Quatermass and set the story in the Fifties, but that would have raised an equal number of continuity issues (Nigel Kneale's own idea of the character's war record was rather more ambiguous and less heroic, and Quatermass, leaving aside the fact that he was married and father of a grown daughter in the 1950s, was never one to fancy younger women). Also, who took the photo of the Doctor that Palmer is developing?
Nostalgia UK: And now we're in the Seventies, so we get to feast our eyes on lots of pretty earth-tone knitwear, wallpaper, shearling coats and Cadbury's tins, plus lovely old tech like Westclox alarm clocks and Kodak slide projectors.
Item Most Likely to Wind Up as a Toy: Nothing toy-worthy this week; for once I'm actually glad Character Options don't go in for cosplay accessories, or they'd probably give us a blue crystal headband.