1 "Where am I going to go, Ipswich?"
Russell T Davies originally re-used this line in one of his early children's dramas, Dark Season in "The End Of The World".
2 Jelly Babies
In "Aliens Of London" a Blue Peter presenter makes a cake in the shape of a spaceship, and he decorates it with jelly babies, the favoured sweet of Tom Baker’s Doctor.
3 Jubilee Pizzas
The episode "Dalek" was loosely based in a Big Finish audio adventure called Jubilee, also written by Rob Shearman. As an in-joke, a set of pizza delivery boxes emblazoned with the logo "Jubilee Pizzas" was created for the episode, but they were never actually seen on screen. Instead, Jubliee Pizzas eventually turned up in Torchwood.
One of the vendors in "The Long Game" is selling Kronkburgers, which had originally appeared in the first ever comic strip to feature in Doctor Who Weekly, "The Iron Legion".
5 Chula Ships
The Chula ship in "The Empty Child" is named after an Indian restaurant in Hammersmith where series one writers Steven Moffat, Rob Shearman and Paul Cornell celebrated after they were commissioned to write for the show.
6 "I'm coming to get you."
A lovely subtle one, this. At the end of "Bad Wolf" after his rant to the Daleks, Doctor Nine promises Rose, “I'm coming to get you." Fitting for an episode which has a Big Brother element to it, as that's the same phrase Davina McCall uses when a contestant is voted out of the house.
When the new Doctor is trying to figure out what to wear at the end of "The Christmas Invasion", he briefly considers David Tennant's costume from Casanova.
8 "Above, between, below."
In "The Five Doctors" the second Doctor recites an old Gallifreyan nursery rhyme: "To Rassilon’s Tower we go, much choose above, between, below." It's the same choice that faces the Doctor and co when they have to get into Battersea Power Station to defeat the Cybermen in "The Age Of Steel". The Doctor says they can find a way in, either "above, between, below."
9 Optional humanity
When Donna asks the Doctor if humanity is optional in "The Runaway Bride", he responds ruefully, "Well, it is for me." This could be a foreshadowing of "Human Nature" but at the time it seemed more likely a sly dig at the Paul McGann TV movie in which the Doctor suddenly reveals that he's half-human.
10 It's in the blood
It's only fitting that in a story like "Smith And Jones", which features a bloodsucking alien, that there's a character called Stoker, in this case Martha’s supervising surgeon. His door plaque even reveals that his first initial is B – Bram by any chance?
11 Pre-emptive Shakespeare
In "The Shakespeare Code", the character of Wiggins is named after Doctor Martin Wiggins, senior lecturer and Fellow of the Shakespeare Institute who's also a big Doctor Who fan. Turns out it was a pre-emptive strike by scripter Gareth Roberts, who realised that if he made any historical errors in the script, Wiggins would be the first to tackle him about them, so he decided "I'd butter him up first."
12 John Smith’s Parents
In "Human Nature" John Smith (the human Doctor) believes his parents are called Sydney and Verity. This was a tribute to the show's real world "parents" Sydney Newman (the main driving force behind the concept of the show) and original Doctor Who producer Verity Lambert. have we mentioned that SFX's Nick Setchfield gave Russell T Davies the idea? (Yeah, about a million times, but hey... it our addition to the legend!)
13 Police Box Windows
In "Blink" copper Billy Shipton mentions that the windows of the TARDIS are too big to be a real police box. This harkens back to Internet criticism of the TARDIS prop when the show first returned and some fans did indeed moan about the size of the windows.
In the "The Sound Of Drums" the Master watches Teletubbies, mirroring a scene from the classic series story The Sea Devils (1972) in which the Master is enjoying an episode of The Clangers.
15 "People of Earth, please attend carefully."
Never let a great cheesy line go to waste. In Tom Baker's swansong, "Logopolis" the Master announced, "People of the Universe, please attend carefully". In "The Sound Of Drums" he was only addressing the people of Earth, but the effect is the same.
16 Passenger 57
Who would have believed the Doctor was a Wesley Snipes fan, but clearly he is as he calls himself "passenger 57" in "Voyage Of The Damned" referencing the Snipes film of the same name.
Ever seen Mary Poppins? Then you'll get the reference here. In "The Fires Of Pompeii" whenever the grumbling volcano starts shaking the ground, the Caecillius family has to get into position to save their valuables from tumbling over, just as the Banks family has to in Poppins whenever their neighbour fires off his cannon.
18 UNIT Timing Troubles
Back in '70s Doctor Who it was accepted that the "contemporary" UNIT stories were actually set just a little into the future. Then in the '80s, forgetful scriptwriters rewrote fictional history and stated that the "70s UNIT stories had in fact been set in the '70s after all. Which probably explains the Doctor's confusion in "The Sontaran Stratagem" when he tells Donna that he worked with UNIT, "in the Seventies...or was it the Eighties?"
19 You say Sonterun, I say Sontaran
In "The Sontaran Startagem" Donna has problems pronouncing the name of the titular baddies. But she wasn't the first. Back on the first Sontaran story, the Pertwee adventure "The Time Warrior" the actor playing the alien and the director disagreed over how to say the word. Actor Kevin Lindsay won when he retorted, "I'm from the bloody planet, I think I know how to pronounce my own name!"
20 "Giant Robot"
In "Planet Of The Dead", nutty professor Malcolm is a massive fan of the Doctor. He claims to have read all the files on him. "What was your favorite?" asks a chuffed Doctor. "The giant robot?" That being the name of the Target novelisation of the Tom Baker story, "Robot"