Fitz and Anji.
Pg 29 On the deck of a racing yacht, Selonart.
Pg 269 A gusty, barren mountainside, Demigest.
Pg 1 "What I got, was Siberia and the Doctor." Time Zero.
Pg 3 "How can he get into the TARDIS?" The Doctor prevented Sabbath from entering the TARDIS in Camera Obscura.
Pg 5 "They had met, at last, in orbit around Proxima II" The Face-Eater. Although see, bizarrely, Continuity Cock-Ups.
Pg 11 "They were verite pictures of seven different men: an old white-haired one, a boyish imp, a velvet-jacketed dandy, a wide-eyed madman, a sad gentle dreamer, a chubby arrogant clown and a sly little schemer." The first seven Doctors.
Pgs 31-32 "After all, we were after Sabbath and after my brief but pertinent run-in with him in Siberia it wasn't likely that this was going to be a pleasure cruise, was it?" Time Zero.
Pg 38 "I was going to need a ton of aspirin though and that is, unfortunately, one commodity that the Doctor never carries in the TARDIS." In The Left-Handed Hummingbird, it's made clear that aspirin could kill the Doctor. (There's a similar scene in The Mind of Evil, but isn't stated what the substance is.)
Pg 40 "'Blum,' he said." Posible reference to fellow EDA author Jon Blum - although Jon's surname rhymes with "plum" and doesn't sound like "Bloom", so possibly not.
Pg 63 "The native blockhead barman, for all his clumsiness, fixed a mean Proximan Ice Tea cocktail." The Proximan colony was seen in The
Pg 91 "I didn't want to think about the dream I'd had, but it kept coming back to me. Reality, splitting apart, dividing." That'll be the next few books, then (The Domino Effect through Sometime Never...).
Pg 118 "The starship was found two months later registered to a company office on Proxima Centauri." The Face-Eater.
Pg 123 Reference to Dave (Escape Velocity).
Pg 179 "They were more powerful than even his masters had suspected." We'll meet his masters in Sometime Never....
Pg 184 "Is it a Knights Templar thing? [...] A remnant of his original organisation perhaps?" The Adventuress of Henrietta Street.
Pg 193 "He remembered his first inklings, centuries back. Staring into the muddied Thames." The Adventuress of Henrietta Street.
Pg 196 "This man who had taken more from him than any other. The Doctor rubbed his chest, perhaps feeling a twinge of pain. The heart of the matter." The Adventuress of Henrietta Street.
Pgs 203-204 "I'd be interested to know how you got it into the TARDIS." It was Trix, in Time Zero, with the model boat.
Pg 224 "The Doctor was thinking about the brief previous visit he had made to this vessel." The Adventuress of Henrietta Street.
Pg 237 "I had left the TARDIS of my own free will. Eighteen months ago, to me at least." Time Zero.
Pg 246 "Didn't you learn anything in Siberia?" Time Zero.
OLD FRIENDS AND OLD ENEMIES
Sabbath, the apes.
NEW FRIENDS AND NEW ENEMIES
Bloom, Valeria, the Warlocks.
The Selonarts, while descendents of humans, have rapidly evolved into the original inhabitants. They have blocky heads and an affinity with water (pg 13).