Unlike previous episodes, there is no scientific explanation of the punishments placed on the family (trapping in a mirror, fixed as a scarecrow).
The Family were all rewarded with a form of immortality, but not the form they were seeking. This is not the first time a Timelord has rewarded a quest for immortality with eternal imprisonment. In The Five Doctors, in the original series, Rassilon rewarded anyone that sought immortality with a place as a stone carving on his tomb.
Baines: He wrapped my father in unbreakable chains forged in the heart of a dwarf star.
The last time that dwarf star alloy was mentioned was in the Fourth Doctor story Warriors' Gate, the slaver ship was constructed from it.
The war memorial scene at the end was filmed at Llandaff Cathedral in Cardiff.
According to director Charles Palmer, the scene involving the aged John Smith took approximately fifteen minutes to shoot (whilst David Tennant had spent around four hours having the prosthetics fitted).
When Latimer opens the watch in front of the little girl, a brief scene from The Runaway Bride can be seen.
Martha: Because I love him to bits, and I hope to God he won't remember me saying that.
Martha: I'm training to be a doctor. Not an alien doctor, a proper doctor, a doctor of medicine.
Joan: Well, that certainly is nonsense. Women might train to be doctors, but hardly a skivvy and hardly one of your colour.
Martha: Oh, d'you think? (holds up hand) Bones of the hand. Carpal bones, proximal row: scaphoid, lunate, triquetral, pisiform. Distal row: trapezium, trapezoid, capitate, hamate. Then the metacarpal bones, extending in three distinct phalanges: proximal, middle, distal.
Joan: You read that in a book.
Martha: Yes, to pass my exams!
Latimer: I just wanted to say goodbye and thank you, because I've seen the future and now know what must be done. It's coming, isn't it? The biggest war ever.
Martha: You don't have to fight.
Latimer: I think we do.
Martha: You could get hurt.
Latimer: Well, so could you, travelling round with him, but it's not going to stop you.
(After dispatching the Family, the Doctor goes back to see Joan)
Joan: You look the same. Goodness, you must forgive my rudeness. I… find it difficult to look at you. Doctor, I must call you Doctor. Where is he, John Smith?
The Doctor: He's in here somewhere.
Joan: Like a story. Could you change back?
The Doctor: Yes.
Joan: Will you?
The Doctor: No.
Joan: I see. Well, then… He was braver than you in the end, that ordinary man. You chose to change; he chose to die.
The Doctor: Come with me.
Joan: I'm sorry?
The Doctor: Travel with me.
Joan: As what?
The Doctor: My companion.
Joan: But that's not fair. What must I look like to you, Doctor? I must seem so very small.
The Doctor: No. We could start again; I'd like that. You and me, we could try at least, because everything that John Smith is and was, I'm capable of that too.
Joan: I can't.
The Doctor: Please come with me.
Joan: I can't.
The Doctor: Why not?
Joan: John Smith is dead, and you look like him.
The Doctor: But he's here, inside. If you look in my eyes.
Joan: Answer me this, just one question, that's all. If the Doctor had never visited us, never chosen this place on a whim, would anybody here have died? (The Doctor cannot answer her) You can go.
Baines: (voice-over) He never raised his voice, that was the worst thing. The fury of the Time Lord, and then we discovered why. Why this Doctor, who had fought with gods and demons, why he'd run away from us and hidden. He was being kind. He wrapped my father in unbreakable chains, forged in the heart of a dwarf star. He tripped my mother into the event horizon of a collapsing galaxy, to be imprisoned there. Forever. He still visits my sister, once a year, every year. I wonder if one day he might forgive her, but there she is, can you see? He trapped her inside a mirror. Every mirror. If ever you look at your reflection and see something move behind you, just for a second, that's her. That's always her. As for me, I was suspended in time and the Doctor put me to work, standing over the fields of England as their protector. We wanted to live forever, so the Doctor made sure that we did.
Joan: (after seeing a glimpse of their possible future together if John stays as he is) The Time Lord has such adventures, but he could never have a life like that.
John Smith: And yet I could.
Joan: If I could do this instead of you, then I would. I had hoped… but my hopes aren't important.
John Smith: He won't love you.
Joan: If he's not you, then I don't want him to.
John Smith: (to Martha) You're this Doctor's companion. Can't you help? What exactly do you do for him? Why does he need you?
Martha: Because he's lonely.
John Smith: And that's what you want me to become?
(Martha, Joan and John are outside the school; the Family are guarding the TARDIS)
Martha: You recognise it, don't you?
Jenny: Come out, Doctor! Come to us!
John Smith: I've never seen it in my life.
Martha: Do you remember its name?
Joan: I'm sorry, John, but you wrote about it. The blue box. You dreamt of a blue box.
John Smith: (starting to cry) I'm… I'm John Smith. That's all I want to be. John Smith, with his life and his job… and his love. Why I can't be John Smith? Isn't he a good man?
Joan: Yes, yes, he is.
John Smith: Why can't I stay?
Martha: But we need the Doctor.
John Smith: What am I, then? Now then? I'm just a story.
Martha: If you want I can go...
The Doctor: Time to move on
Latimer: (about the Doctor) He's like fire and ice and rage. He's like the night and the storm in the heart of the sun…
John Smith: Stop it.
Latimer: He's ancient and forever. He burns at the centre of time and he can see the turn of the universe.
John Smith: Stop it! I said, stop it!
Latimer: And… he's wonderful.
John Smith: How can you think I'm not real? When I kissed you, was that a lie?
Joan: No, it wasn't. No.
John Smith: This Doctor sounds like some… some romantic lost prince. Would you rather that? Am I not enough?
Joan: Tell me. In this fairytale… who are you?
Martha: Just a friend. I'm not… I mean, you haven't got a rival, as much as I might… just his friend.
Joan: And human, I take it?
Martha: Human, don't worry and, more than that, I don't just follow him around. I'm training to be a doctor. Not an alien doctor, a proper doctor. A doctor of medicine.
Joan: Well, that certainly is nonsense. Women might train to be doctors but hardly a skivvy and hardly one of your colour.
Rocastle: You speak with someone else's voice, Baines. Who might that be?
Baines: We are the Family of Blood
Rocastle: Mr. Smith said there have been deaths.
Baines: Yes, sir, and they were good, sir.
Rocastle: Well, I warn you. The school is armed.
Baines: All your little tin solders. But tell me, sir… will they thank you?
Rocastle: I don't understand.
Baines: What do you know of history, sir? What do you know of next year?
Rocastle: You're not making sense, Baines.
Baines: 1914, sir. The Family has travelled far and wide looking for Mr. Smith and… the things we have seen. War is coming. In foreign fields, war of the whole wide world, with all your boys falling down in the mud. Do you think they will thank the man who taught them it was glorious?
(At the school gates, Rocastle and Phillips encounter Baines, Jenny and several Scarecrow soldiers)
Rocastle: So, Baines, and one of the cleaning staff. There's always a woman involved. Am I to gather that some practical joke has got out of hand?
Baines: Headmaster, sir. Good evening, sir. Come to give me a caning, sir? Would you like that, sir?
Rocastle: Keep a civil tongue, boy.
Phillips: Now, come on everyone. I suspect alcohol has played its part in this. Let's all just calm down. Who are these friends of yours, Baines, in fancy dress?
Baines: Do you like them, Mr. Phillips? I made them myself. I'm ever so good at science, sir.
Rocastle: (after being told of the imminent attack on the school) Mr. Phillips, with me, we shall investigate.
Martha: No, but it's not safe out there.
Rocastle: Mr. Smith, it seems your favourite servant is giving me advice. You will control her, sir.
Martha: (as the village hall clears; to John Smith) Go on, just shift.
John Smith: What about you?
Martha: Mr. Smith, I think you should escort your lady friend to safety, don't you?
(Martha points the alien gun at Baines)
Baines: Would you really pull the trigger? Looks too scared.
Martha: Scared and holding a gun. It's a good combination. D'you wanna risk it?
(As John Smith stumbles around the Family of Blood's spacecraft, pleading for his life)
Jenny: He didn't just make himself human - he made himself an idiot.
Baines: Same thing isn't it?
(when Martha runs out of the Village Hall, she sees John Smith still standing at the gate)
Martha: Don't just stand there, move! God you're rubbish as a human! Run!
(Upon returning to the school, John Smith raises the alarm by ringing the bell)
Hudson: What's the matter?
John Smith: Enemy at the door, Hudson, enemy at the door!
Turkey: December 26, 2010 on CNBC-e
Overnight viewing figures for this episode were 6.6 million, with a final viewing figure of 7.21 million.
Joan Redfern is another who has declined the offer of travelling with the Doctor. Others who have also declined the offer are Dr. Grace Holloway in Doctor Who: The Movie (1996), Mikey Smith in World War Three [Season 1, Episode 5](2005) and Donna Noble in The Runaway Bride (2006)
Unlike Human Nature, David Tennant is only credited as 'The Doctor' in the end credits of this episode.
Tim Latimer: Oh, yes, sir, every time.
This is similar to the response given by the Ninth Doctor to the Dalek Emperor ("Coward, every time!") in "Parting of the Ways"
John Smith: So what am I then? Nothing? I'm just a story?
Subtle self-reference: John Smith worries that he is just a story, whereas Doctor Who actually is a story.
Joan: Can you change back?
The Doctor: Yes.
Joan: Will you?
The Doctor: No.
This is very similar to what the Doctor said to Rose in the Children in Need special of 2005.
Rose: Can you change back?
The Doctor: Do you want me to?
The Doctor: Oh.
Rose: Can you?
The Doctor: No.
Rocastle: We need water for the Vickers gun.
The Vickers .303 Machine Gun became the standard in the British Army from 1912 to 1960. Being water-cooled, it could fire continuously for long periods. Heat engendered by the rapid fire soon boiled the water and caused a powerful emission of steam, which was condensed by passing it through a tube into a canvas bag of water. By this means the gun could continue to fire without a cloud of steam giving its position away to the enemy.
Vicar: Age shall not weary them, nor the years condemn.
At the going down of the sun and in the morning,
We will remember them.
This is a quote from Laurence Binyon's poem 'For The Fallen' (1914). Whilst seven stanzas long, the third and fourth stanzas (as can be heard quoted in this episode) are often used at Remembrance Day and Remembrance Sunday services, as well as ANZAC Day, as seen here.
At the final war memorial scene, both the Doctor and Martha are seen wearing artificial red poppies. This is a mark of respect for all those who have fallen in war, although traditionally associated with the First World War. The poppy's significance to Remembrance Day is a result of John McCrae's poem 'In Flanders Fields' (1915). The poppy emblem was chosen because of the poppies that bloomed across some of the worst battlefields of Flanders in World War I, their red colour an appropriate symbol for the bloodshed of trench warfare. Artificial poppy wreaths are laid at cenotaphs and war memorials on Remembrance Day and Remembrance Sunday each November.
The Doctor: In June 1914, an Archduke of Austria was shot by a Serbian and this then led, through nations having treaties with nations, like a line of dominoes falling, to some boys from England walking together in France on a terrible day.
On 28 June 1914, Gavrilo Princip, a Yugoslav student, killed Archduke Franz Ferdinand, the heir to the Austro-Hungarian throne, in Sarajevo. The assassination in Sarajevo set into motion a series of fast-moving events that escalated into a full-scale war that lasted from 1914 to1918. Over nine million people died in the conflict. Among them were English boys who had lied about their age in order to enter into battle for King and Country.