The Fourth Dimension
Julian Bleach, who plays Davros, appeared in an RSC production of The Tempest opposite Patrick Stewart... who was one of several actors mistakenly rumoured to be playing the evil genius. Sir Ben Kingsley was another name incorrectly attached to the role. Julian previously appeared in the Torchwood episode Out Of The Rain, as the Ghost Maker.
Keep It In The Family
Eve Myles, who plays Gwen Cooper in Torchwood, also played Gwyneth in series one episode The Unquiet Dead. The Doctor comments on spacial genetic multiplication when he asks her about her family coming from Cardiff.
According to Russell T Davies, "It's not familial as we understand it. There's no blood tie. Spatial genetic multiplicity means an echo and repetition of physical traits across a Time Rift."
The Cult Of Skaro
That's now two members now of the former 'Cult of Skaro' that have seen the Daleks for what they truly are - first Dalek Sec in Evolution of the Daleks (2007), and now Dalek Caan.
Accidents Will Happen
What happened to Davros has only ever been referred to by himself as 'an accident'. The original draft of the script did show Davros as the man he once was, and what happened to him...
Davros recalls seeing Sarah Jane Smith on Skaro, when he first created the Daleks. This is, of course, a nod to the classic 1975 story Genesis of The Daleks, in which the Fourth Doctor and Sarah Jane travelled to Skaro in order to stop the Daleks ever being created.
It's sometimes been claimed that TARDISes are designed to be flown by six pilots (eg, in the 1992 novel Doctor Who - Cat's Cradle: Time's Crucible), although this is the first time this has been confirmed in the TV series.
Grow Your Own
In the original script, the Doctor gave Rose's Doctor a small piece of 'coral' from the TARDIS so that he could create his own Time/Space machine from it.
What's In A Name?
'Osterhagen' just happens to be an anagram of 'Earth's Gone'.
For the Bad Wolf Bay scenes towards the end of the episode, the crew returned to the beach at Southerndown, a few miles west of Cardiff. They previously filmed there for Rose's departure in Series Two's Doomsday.
Those of you who have been slightly bothered for the last 12 years by the comment made by the Eighth Doctor in the TV Movie that he was half human on his mother's side, can probably breathe a sigh of relief now. The Doctor #2 seems shocked that he has become uniquely half human due to the biological metacrisis wth Donna, strongly suggesting that he never was before.
If you were wondering about some of the dialogue during Martha's trip to Germany, Script Editor Lindsey Alford and Kevin Myers offer these handy translations!:
FX: way off in the distance, DALEKS, in the air, gliding slowly through the trees.
DALEKS: Exterminieren! Exterminieren! Halt! Sonst werden wir Sie exterminieren! Sie sind jetzt ein Gefangener der Daleks! Exterminieren! Exterminieren!
Translation: Exterminate! Exterminate! Stop! Or you will be exterminated. You are a prisoner of the Daleks. Exterminate! Exterminate!
Martha heads off in the opposite direction. Scurrying away into the darkness. On a mission.
OLD WOMAN: Hier ist niemand. Was immer Sie wollen, gehen Sie fort. Lassen Sie mich in Ruhe.
Translation: There's no one here. Whatever you want, just go away. Leave me alone.
The OLD WOMAN's hostile, standing on the path.
MARTHA: Ich heisse Martha Jones. Ich komme von UNIT. Agentin fuenf sechs sechs sieben eins, von der medizinishen Abteilung.
Translation: I'm called Martha Jones. I come from UNIT. Agent 5, 6, 6, 7, 1. Medical officer.
OLD WOMAN: Es hiess Sie kaemen vorbei.
Translation: They said you might come.
OLD WOMAN: Sie sind der Albtraum. Nicht die anderen, Sie! Ich sollte Sie umbringen, am besten gleich jetzt!
Translation: You are the nightmare. It's not them, it's you! I should kill you right now!
MARTHA: Then do it.
And Martha just steps into the lift.
The Old Woman lowers her gun, defeated, shaking.
OLD WOMAN: Marta. Zur Hoelle mit Dir.
Translation: Martha. You're going straight to Hell.