Roots: The story title comes from the pamphlet series of the same name issued by the British Government in the late Seventies and early Eighties. When the Wind Blows - both the comic and film (Peggy and Albert's son Raymond is, presumably, named after author Raymond Briggs, while Peggy may borrow her name from Dame Peggy Ashcroft, who voiced the female lead in the 1986 animated adaptation), Threads. Withnail and I (the charging bull, "We've come on holiday by accident' paraphrases the film's "We've come on holiday by mistake!") Bizet's Carmen. The works of H P Lovecraft. Hex compares the scenario to Groundhog Day (as Morris' not-dissimilar Eternal Summer also does)
Dialogue Triumphs: Hex on the Doctor: "Sometimes he gets so close to the monsters it's hard to tell them apart."
Continuity: Moloch is the oldest and most powerful of the Elder Gods, born in the fires of creation, and a god of chaos. His agents were instructed to destroy the Earth and take the form of several real life humans including, most recently, Albert and Peggy Marsden, but are trapped in a pocket dimension created by the Doctor. The dimensional prison takes the form of a ten-day time loop and only exists as long as the Elder Gods are trapped within it, apparently preventing Moloch from freeing them. Inside it, the Doctor means them to understand what it is to live and die as mortal humans, and has promised to release them once they can do this; they have been trapped for several hundred years in their efforts, however.
In world events created by Moloch and presumably erased by the Doctor's actions the Berlin wall does not fall and Communism remains. Popular risings in the Eastern bloc lead to the Soviet Union's General Secretary Vladimir Kruschev ordering talks and troops to fire on protesters. When American bases in West Berlin come under Soviet control the United States issues an ultimatum and, when this is ignored, they bomb a town on the border of West Germany, escalating the likelihood of nuclear war, which in the Doctor's trap comes to pass.
The TARDIS Hex and Ace are in is still white; the Doctor's TARDIS is black.
Links: Project Destiny / A Death in the Family (Aristedes), House of Blue Fire (Sally) Hex mentions his time in the Arctic (Lurkers at Sunlight's Edge). The Doctor mentions having already seen "one nuclear wasteland" in the future - possibly he is referring to Skaro (The Daleks / Genesis of the Daleks) or even Oseidon (The Android Invasion / The Oseidon Adventure) rather than Earth.
Untelevised Adventures: The Doctor says he has seen a nuclear-ravaged future (though he could be talking about Skaro)
Location: A side-dimension modelled on Yorkshire, 1989.
The Bottom Line: "It's only war if we give them a chance to fight back."
Chilling in its early episodes, and highly reminiscent of Morris' Eternal Summer, but once the sci-fi trappings reveal themselves the story inevitably changes. That said, it's one of two halves, and both of those are strong enough on their own. All the regulars are really hitting their marks (Aldred and Olivier especially), and the final scene is a real stunner. A brilliant opener to the trilogy and another gripping story from one of BF's most reliable writers.