The Oracle of the Lost can answer any question. Jason Kane has discovered an obscure planetoid. Irving Braxiatel is looking for a new place to house his collection. The Advanced Research Department on Dellah is under seige. Benny is connected to all these events, but in ways she can't possibly forsee.
Jason, Chris (second regeneration), Irving Braxiatel, Clarence.
Pg 197 Irving's box dematerialises on its way to the Time Lords.
Chris also appears in an unnamed location and a Time Lord in a monk's habit comes and goes.
Tears is a conclusion to the Benny NAs, in lots of ways. It features the concluding fates of many of the minor characters who'd populated the Benny universe and begins to wind up the war. It's in the Gods arc, so Where Angels Fear and Dead Romance are referenced quite heavily. There are also references to Dragons' Wrath, Walking to Babylon and The Medusa Effect.
Pg 1 Edward Watkinson. Benny holds the Watkinson Chair of archaeology (which we find out on page 92 was endowed by Dr Follett) as mentioned in Oh No It Isn't!
Pg 9 The Treaty is between the People and the Time Lords and was made by Chris Cwej in Dead Romance.
Pg 10 The Babylon incident is the events from Walking to Babylon, where a treaty with the Time Lords was also broken and nearly caused a war like the one they're worried about.
Pg 11 In Dead Romance, Chris believed the People could have time travel by tomorrow lunchtime. It's not that simple though and we later find out it's their lack of telepathy that's slowing them down.
Pg 15 Neo-Aretians. Ice Warriors in the Benny universe, mentioned in The Medusa Effect.
Pg 16 The Advanced Research Department was first seen in Oh No It Isn't! and later doing lots of shady stuff, most notably in Mean Streets and The Medusa Effect.
Pgs 22-23 Benny went back for her cat in The Mary-Sue Extrusion and had the titular 'Mary Sue', or memory wipe/personality transplant.
Pgs 41-42 The extract from Happy Endings was written by Justin Richards for the all-authors chapter (page 256)
Pg 64 Theatre of War has the Braxiatel location on a small planet previously known as KS-159. It's rumoured there that Braxiatel won it at cards, which we see later in this novel.
Pg 65 "I remember you telling me that ancient civilisations don't leave their treasures [...] just lying around for people to discover." This was a central theme from Beyond the Sun.
Pg 75 Vega Station from Demontage. The events are contemporary, since Newark Rappare leaves Demontage to get killed in the opening section of Dragons' Wrath.
Pg 78 Thanaxos. Location in The Mary-Sue Extrusion where most of the Dellahan refugees went sent.
Pg 84 Yellow sticky notes are still being used by Benny. Initially they were pink in Love and War, but later changed to yellow.
Pg 167 Braxiatel's brother is, of course, the Doctor. The Doctor had already hinted at some familial relationship in The Empire of Glass.
Pg 196 The six-sided box that disappears might be a four-dimensional tesserect, being 3 dimensional plus time. The Doctor used something similar to contact Ace in Deceit.
Pg 197 "Harsh, discordant scraping sound" Dematerialisation noise, ala the TARDIS.
Pg 198 A Time Lord in a monk's habit. Unlikely to be the Meddling Monk, but with the changing allegiances of Dead Romance, you never know.
Pg 199 Chris is fresh from the events of Dead Romance, left in the 'real' universe. He returns to an irradiated zone intending to regenerate, as discussed in Dead Romance. At the end of that novel he was sick, his hair falling out, losing weight and had radiation poisoning.
Pg 200 "Give the process a small push" Very reminiscent of Cho-Je's words in Planet of the Spiders.
"Substances" cocaine, maybe? Chris is trying to induce regeneration to have the battle-armaments like Kiste in Dead Romance. These are the effects that are negated here.
Pg 201 "Giant teddy bear" was the body bepple Chris had in Original Sin.
"Pan-dimensional war machine" was the end result of regeneration in non-Time Lords in Dead Romance (eg Khiste).
Pg 228 Sara!qava! was the man/woman from The Also People who showed an interest in Benny (and whose daughter was pregnant with Chris's child).
Pg 230 "Vulcan nerve pinch" is Spock's disabling grip from Star Trek.
Pg 241 "Love's Labours Wonne" is the title of a supposed lost play of Shakespeare's. It's the sister play to "Love's Labour's Lost" and was mentioned in Theatre of War.
Osterling's "The Good Soldiers" was the missing play found in the Dream Machine and pivotal to the conclusion of Theatre of War.
The Library of St John the Beheaded was seen in All-Consuming Fire and Millennial Rites.
Pg 252 The Ninjucoids appeared in Ghost Devices.
Pg 269 "When Mastrov came to kill you." This occurred in Dragons' Wrath.
Pg 270 "When God once miraculously managed to take over Joseph to give her a message" This occurred in Walking to Babylon, page 49.
OLD FRIENDS AND OLD ENEMIES
Pg 9 God is the all-powerful computer that controls the Worldsphere and who has featured in lots of Benny NAs (and sort of started the war).
Pg 10 B-Aaron was seen in The Also People (where all the ships were named after New Adventures authors, so the B-Aaron got the honour of an author namechecking himself) and rescued Benny from Dellah in Where Angels Fear.
!Cin-ta!x is the People's time-travel guru in Walking to Babylon. He leaves the People at the end of that, hence the references to his returning for the new experiments.
Pgs 16-18 Skutloid, Drexton and Garshal are the Ice Warriors from The Medusa Effect.
Pg 17 Silvera is head of the Advanced Research Department. He was seen in Mean Streets and The Medusa Effect.
Mira was seen briefly in Ship of Fools and was with Jason at the conclusion of The Mary-Sue Extrusion.
Pg 25 Renee was a fellow academic of Braxiatel's in Where Angels Fear. She was a lot more earthy than Brax, however.
Pg 38 Doctor Divson Follett was first mentioned in Oh No It Isn't! and seen in Dragons' Wrath onwards as Benny's boss in the archaeology department on Dellah.
Pgs 46-47 Joseph was Benny's porter, introduced in Oh No It Isn't!
Pg 81 Dr Emilia Winston was first seen in Dragons' Wrath.
Pg 107 !C-Mel was the ship from The Also People who committed the unthinkable - murder. Named for Andrew Cartmel, interestingly enough.
Pg 130 Trooper Jinkel. It's never stated outright, but the troops might be Chelonians (from Highest Science and elsewhere) with names like this.
NEW FRIENDS AND NEW ENEMIES
The Oracle of the Lost, a statue on asteroid KS-159 that can answer any question.
Pg 15 Dellah, present day, in ruins.
Pg 64: Asteroid KS-159, later the home of the Braxiatel Collection.
Pg 129 Paracletes (reference only - it's where Watkinson went on an expedition, eighty years ago)