The Doctor Dances
Roots: War films (the gas-mask imagery), Jack's missing memories are reminiscent of Commander Sinclair in Babylon 5. Algy is named in this episode, and therefore exposes a nod to the Biggles novels. Eric Drexler's exponentialist views on molecular nanotechnology, explained in his book Engines Of Creation and popularly misrepresented as the grey goo scenario. Oh, and that Star Trek: The Next Generation episode with nanites in it. Jack riding the bomb is a pretty strong tip of the hat to Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb. The nanogene problem is very similar to the Red Dwarf episode, "Nanarchy" in which the nanobots that are supposed to keep Kryten the robot in a state of good repair go haywire and miniaturize Red Dwarf. The Sorcerer's Apprentice (unexplained phenomena that turn out to be caused by out-of-control nanobots).
Goofs: Why does Nancy try to escape the house through the back door, where the air-raid shelter is, rather than through the front where there won't be anybody about?
If Jamie's communication powers can use anything with a speaker grill, then how does he affect the typewriter?
Why does Rose think that the Doctor doesn't dance? She saw him dancing for at least a couple of seconds in The End of the World. [It's another Double Entendre.]
The Doctor again gives his age as 900, when he's over 953 (Time and the Rani), and the novels mean that he has to be at least 1200.
The Doctor talks about Nancy being 20 or 21 now, and 16 or 17 when Jamie was born, and then goes on to talk about what happened when Jamie was born as her being a "teenaged single mum in 1941" - surely he should be saying that this was in the 1930s.
The nanogenes are described as being "subatomic", which would mean that there's nothing to make them out of, and they'd be too small to carry out repair work on human beings. [Maybe they're the genetic code that builds nanites which are big enough to do the work. They may be "engineered" subatomic particles capable of strongly interacting or otherwise exerting influence (similar to mesons or valence electrons)].
Why does Jack take the bomb into his ship rather than simply drop it off somewhere safe? Hey, why not use the tractor beam or teleport to get himself off the ship as soon as it's safely away from anywhere it could cause damage.
Where did Rose learn 40's style dancing? [Either she's a big fan of Strictly Come Dancing, or there was some kind of dancing club at her school.]
Jack's ship has what appears to be a painted cloth where you'd expect to see the outside view.
The ambulance's distress call seems to be ignored - surely the nanogenes wouldn't have removed the Chula programming from their victims, so they would still be programmed to defend it.
Just how does the Doctor work out that the nanogenes have become airborne?
The trains in the railway station/bomb site have post-war livery on them.
Why does Nancy ask to use the Bathroom? Most homes in the war had an outside toilet and a tin bath rather than a bathroom, and besides, it's an Americanism that never caught on in the UK.
If the nanogenes can read DNA accurately enough to trace family lineages, why wouldn't they use this information to figure out what human beings are supposed to be like in the first place? Even a dead child's DNA would easily yield this information. That they instead use a process that can't tell flesh from rubber, the distinction they would surely have to make constantly under battlefield conditions, is particularly implausible.
If the nanogenes make all the humans they affect into warriors, then why isn't the Doctor concerned about the potential consequences of this?
Double Entendres: The Doctor and Rose's conversation about dancing whilst Jack is distracting Algie. Also, Nancy's comments about Mr Lloyd messing about with the butcher.
Dialogue Triumphs: The Doctor: 'I'm really glad that worked. Those would have been terrible last words.'
The Doctor: 'It's got the power of a god, and I just sent it to its room.'
Whilst fleeing for their lives: The Doctor: 'Don't drop the banana.'
Jack: 'Why not?'
The Doctor: 'Good source of potassium.'
Ernie: 'You can't even read or write.'
Jim: 'I don't need to. I've got a machine.'
Rose: 'Why is is always the great looking ones who do that?'
The Doctor: 'I'm making an effort not to be insulted.'
Rose: 'He saved my life. Blokewise that's up there with flossing.'
The Doctor: 'I've travelled with a lot of people, but you're setting new records for jeopardy friendly.'
Rose on dancing: 'You'll find your feet at the end of your legs. You may care to move them.'
Rose: 'What about that bomb?'
The Doctor: 'Taken care of it.'
The Doctor: 'Psychology.'
Mrs Harcourt: 'My leg's grown back. When I come to the hospital, I had one leg.'
Doctor Constantine: 'Well, there is a war on. Is it possible you miscounted?'
The Doctor: 'History says there was an explosion here, and who am I to argue with history?'
Rose: 'Usually the first in line.'
Jack: 'They stayed in touch. Can't say that about most executioners.'
Memorable Moments: Mr Lloyd tells Nancy that he's called the police after her break-in and stealing of his food, but she stands up to him and demands more stuff off him. Later on, she refuses to believe that Rose is from London in 50 years time because she isn't German.
Continuity: Jack's planned con was that he would sell a time agent a piece of space junk, collect some money up-front, and then have a German bomb fall on the site before the Time Agent works out it's space junk. He carries a sonic blaster from the factories of Vilengard. It has a digital blast pattern - which is square. Its special features really drain the battery. He tries to con the Time Agents because they've stolen two years of his memories. His stolen Chula warship has OmCom capabilities (it can use any device with a speaker grill), and a stasis field, though that won't last forever. It has no escape pods, but does have a sink. It is programmed with emergency protocol 417, which creates a cocktail of some description. The last time he was sentenced to death, he ordered 4 hyper-vodkas for breakfast, and woke up in bed with both his executioners, and they stayed in touch. It is destroyed when the German bomb explodes inside.
The sonic screwdriver can set up a resonation pattern in concrete, which can loosen any bars embedded in that concrete. Set at 2428 gigs it re-attaches barbed wire.
Chula medical ships are packed full of nanogenes, enough to rebuild a species. Once they've crashed, the emergency protocols come into operation. Any tampering with the ship alerts all Chula warriors in the vicinity. If they don't recognise the local species, they will rebuild from the template of the first example they come across, and inflict that pattern on others of that species - so if the template is a dead and badly mutilated person, they will seriously muck up. They also include modifications - super-strength, the ability to OmCom (speak through any device with a speaker grill), and program them to obey Chula commands.
Rose is supposedly Mickey's girlfriend, at least until Boom Town. However, her love life is rather more complicated (or maybe shallow - but then she is only 19) than this, as she seems to fall for every pretty boy she meets. In Dalek she falls for Adam, insisting that the Doctor take him into the TARDIS, and in The Long Game the Doctor describes Adam as Rose's boyfriend. However, she dumps Adam when the Doctor does. In The Empty Child, Rose instantly falls for Captain Jack, and doesn't seem to have second thoughts, even when he admits he's a con-man. It's only when the Doctor points out the rather different sexual habits of Jack's native time that Rose seems to treat him more as a friend than a likely lover. In fact, according to the psychic paper, even though she has a boyfriend she considers herself available. However, by Boom Town, she definitely wants to spend time, and even share a hotel room, with Mickey. In fact, as soon as the crisis is finished, she rushes back to him - despite his relationship with Trisha Delaney. However, both there and in The Parting of the Ways, Rose appears to be blind to the strength of Mickey's feelings towards her - despite commenting on them in Father's Day, as in both Boom Town and The Parting of the Ways she completely fails to listen to what he says about their relationship.
There are some who think that there might be a romantic relationship between Rose and the Doctor. There are a number of scenes where Rose appears to be flirting with him (though given that she is the flirtatious type, it is unwise to place too much weight on this), and her friendship with him is stronger than any of her romantic relationships. However, in Aliens of London, both the Doctor and Rose are both horrified at even the suggestion that they are in a sexual relationship. I think it's safe to say that the ninth Doctor doesn't have any romantic feelings for Rose, especially given this incarnation's general disdain for humanity, and any romantic feelings that Rose may have for the Doctor are not reciprocated.
Links: Rose mentions the Doctor blowing up her job (Rose). The story is the second half of a two parter, the first part being The Empty Child.
Location: London, 1941; Jack's ship in the Vortex.
Unrecorded Adventures: The Doctor once visited the weapons factories of Vilengard in the 51st Century. He implies that he was the one who made the main reactor go critical. He also knows that there is now a banana grove in its place. Rose compares the Doctor to Santa Claus, and he asks her "who says I'm not. red bicycle when you were 12."
The Bottom Line: 'Everybody lives!' A brilliant second half to a great story. The strong atmosphere is maintained from The Empty Child, and all the plot threads resolved. The plot is strong, and the characterisation exemplary. In short, you can't fault it.