The Doctor (Peter Capaldi) has finally returned to our TV screens this Easter weekend for a new run of adventures, kicking off series ten with a wild chase across the galaxy with new companion Bill Potts (Pearl Mackie) and Nardole (Matt Lucas).
Amidst the excitement however, you might have missed a few things that were lurking in the background. Here's a rundown of our favourite Doctor Who throwbacks, references and, yes, Easter eggs hidden in The Pilot...
There are photos of The Doctor's wife and his granddaughter on his desk
The Doctor clearly isn't ready to let go of his wife River Song (Alex Kingston) or his original Tardis passenger, granddaughter Susan (Carole Anne Ford), and has framed photos of them sitting on his office desk. Showrunner Steven Moffat told us that's partly because the Time Lord sees this as the kind of human tradition that will help him blend in while he's playing the part of a university lecturer. But Susan's inclusion has added significance, given that Bill's arrival is supposed to essentially reboot Doctor Who, returning us to a moment that echoes The Doctor's adventures with his first ever travelling companion.
There's a whole pot of sonic screwdrivers just lying around
Who needs pens when you've got that many sonics, eh? Nardole even uses one to "run interference" when the gang try to outrun Heather among the Daleks – although some of these look like they'd wouldn't be out of place in the office of an ear, nose and throat specialist either.
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And a raven lurking behind them...
Here's hoping nobody has to do a Clara and face the raven this time around, eh? EH?
And this may be pushing it but could that strange model in the glass case perhaps be a representation of The Doctor's time stream, as seen in The Name of the Doctor? Nope? Just us then...
Beethoven's bust is back – and so is his Fifth Symphony
If you look very closely you'll spot a bust of the composer in the background in the Doctor's office at the university, and this isn't the first time its popped up in the series. The same statue can be seen in the Tardis back in series 9 episode Before the Flood when The Doctor uses the composer to illustrate an interesting phenomenon called the Bootstrap Paradox.
That was accompanied by the Time Lord banging out the chords of Beethoven's Fifth Symphony on his electric guitar, which is also the first thing new companion Bill hears when she first enters his office in The Pilot.
The Bard is back too
Talking of busts of famous people, we all know The Doctor is a huge fan of William Shakespeare, so it's no surprise to see his old pal (from The Shakespeare Code) also given top Billing in his office. Could that also be a sly reference to his new companion?
The Doctor's blackboard is borrowed from Class's Miss Quill
While the future of Doctor Who spin-off Class may be in doubt, the production team are at least getting some use out of its props.
Look closely, and you’ll spot that the distinctive silver-framed blackboard the Doctor uses for his ever-popular lectures previously saw some action in Coal Hill school, specifically in the classroom of alien teacher Miss Quill. Hopefully he asked before borrowing it…
Nardole's explanation of how the Tardis works is borrowed from the Fourth Doctor
"First you have to imagine a very big box fitting inside a very small box. Then you have to make one," Nardole tells Bill when trying to explain how the Tardis can possibly be bigger on the inside. "It's the second part people normally get stuck on…"
That's a slightly more simplistic version of a thought experiment used by the Fourth Doctor when trying to demonstrate the same phenomenon to his companion Leela in 1977 adventure Robots of Death.
The Doctor takes two boxes and places the larger one on the Tardis console. Taking the smaller box to a distance where perspective makes it appear bigger, he tells Leela “If you could keep that [larger box] exactly that distance away and have it here, the large one would fit inside the small one.”
“That’s silly,” says Leela.
“That’s trans-dimensional engineering,” replies the Doctor.
Bill may have been writing essays about time travel
Take a closer look at the scene where Bill is flicking through her essays for The Doctor and you'll see she's been working on topics including 'Quantum statistics of light' and 'Laser cooling of ions: atomic clocks and quantum jumps'.
Quantum physics has long been linked to explanations for time travel, and is often adopted by researchers who are attempting to get their heads around the Grandfather Paradox (whereby a time traveller goes back in time, prevents their grandparents meeting, prevents their own conception and thus could never have existed in order to travel back in the first place).
And her foster mum has actually met The Doctor before
Moira is an old acquaintance of the Time Lord, albeit from a very different space and time – here's where and when...
There's a clever reference to the dearly departed Clara Oswald
And a final nod to Back To The Future
"What the hell!" Two time travelling doctors each make a decision to tear up the rule book – read our full explanation here.
Doctor Who series 10 continues on BBC1 on Saturday nights