Another member of Mary's species was later seen in The Sarah Jane Adventures episode "Invasion of the Bane". In that episode, their homeworld was revealed to be Archetine V.

According to Mary, Tosh has been working for Torchwood for three years. This means that she was probably working undercover in Albion Hospital when she encountered the Doctor in the 2005 Doctor Who episode "Aliens of London".

According to Tosh, the soldier died "196 years, 11 to 11 and a half months" prior to the events of this episode, almost immediately after Mary's arrival on Earth. As this was shown to have occurred in 1812 in the pre-credits sequence, this episode most likely takes place in either late 2008 or early 2009.

Jack: Once, just once, I’d like to walk into one of these tents and find it’s a party, with food, and drink, and dancing; a girl crying in the corner.

(finding a skeleton)
Gwen: Any idea what it is.
Jack: Not a clue. Could be a weapon or a really big stapler. Hows our friend there?
Owen: She's dead.
Jack: Yeah, thanks, Quincy.

Gwen: (helping Owen up) Oh you so light, you like a girl!
Owen: I’m not light. I’m wiry. The fat girls go mad for it. But I guess I don’t need to tell you that

Owen: You know what, Tosh, sometimes I think even that stick up your arse has got a stick up its arse.

Mary: Toshiko Sato, born in London 1975, moved to Osaka when you were two then back to the UK in 1986. Parents in the RAF, Grandfather worked at Bletchley Park, very impressive. University, blah blah, snapped up by government scientist think-tank when you were twenty, recruited to Torchwood three years ago.

Tosh: What’s most amazing are the similarities with our own culture, but that can be horrible ‘cause we find lots of weapons and it just makes you think "my God, everything wages war". It’s not just a trait of ours, but a trait of existence. And it makes you feel so hopeless. But then there are times, we found this thing, it was about A4 size and it had all these symbols on it and it took me about three months to translate. It was a letter someone had written to his family; to his children to say how much he was missing them. It just made me cry because I thought, "even across these unimaginable distances, there are fundamentals that stay exactly the same". And there’s no-one to talk to about this. I mean, the guys at work, they’re great but, they don’t see it the way I do. (Pauses) I could be fired just for telling you that.

Gwen: (thinking about Tosh) Oh, sweetheart, the jeans and the boots thing has really kind of had its day.

Ianto: (thinking) Can't imagine a time when this isn't everything. Pain so constant, like my stomach's full of rats. Feels like this is all I am now. There isn't an inch of me that doesn't hurt. (aloud; cheerily) I’m about to brew some of Jack’s industrial strength coffee. Would you like a cup?
Tosh: I’m… fine, thanks Ianto.

Gwen: As you may remember, at the building site, Owen said that this was a woman killed by a single gunshot.
Owen: Yeah, I’d been like a minute.
Gwen: Since then he’s had to tweak some of his initial conclusions. This first being that this isn’t in fact a woman, but a man.
Owen: A young man. A very girly man.
Gwen: But, still, ultimately a man. Then there was the cause of death. Owen said GSW. The correct answer was…
Owen: Unidentified trauma. But…
Tosh: Unidentified trauma?
Gwen: You see it in RTAs. When something like a steering column or a post goes into a body at great velocity. But the one thing that could be ruled out was…
Owen: Gunshot wound.
Gwen: Gunshot wound. Was there in fact any part of your prognosis that was right?
Owen: I got that it was… a skeleton.

Owen: So I started looking into devil worship and stuff from that era, see if there’s anything about plucking out hearts. And would you believe it, there’s nothing. They ate eyeballs, they drank blood, they had sex with animals but they did not pluck out each other’s hearts, ‘cause obviously that would have been weird.

Tosh: I’m giving them the pendant.
Mary: Right, let’s...
Tosh: You’re right. It’s not like reading someone’s diary. It’s so much worse, and it makes me feel dirty and ashamed and now I’m spying on my friends.
Mary: Some friends.
Tosh: What’s that supposed to mean?
Mary: They pity you. They exclude you.

Tosh: So I’m shagging a woman and an alien.
Mary: Which is worse?
Tosh: I know which one my parents would say.

Tosh: I can’t stand it anymore. The weight of it, the depravity, the fear, it fills me up. It’s in my mouth, in my hair, my eyes, like I’m drowning in ink. And even when I don’t have the pendant on, it feels like there’s nothing, I can’t forget the things I’ve seen, the things I’ve heard. It’s like a curse, something the gods sent to drive someone mad. I had hope, I’d see something, a little random act of kindness, and make me think we were safe. Some essential good in us. There isn’t. It’s like one of the Weevils, look inside and there’s just a great chilling scream. You were right. Everything you said about us: we’re frightened and callous and I can’t be a part of it any longer. I don’t know what to do. Tell me what to do.
Mary: Get me into Torchwood.

Mary: You smell... different than them.
Jack: That's nothing. It's when you compare teeth with a British guy. That's when it's really scary.
Mary: What are you?
Jack: I don't know.

Tosh: Has she gone home?
Jack: I reset the coordinates.
Tosh: Where to?
Jack: To the centre of the Sun. It shouldn't be hot, I mean, we sent her there at night and everything.
Tosh: You killed her.
Jack: Yes!

Tosh: Why couldn’t I read your mind?
Jack: I don’t know. Though I could feel you scrabbling around in there.
Tosh: I got nothing. It’s like you were… dead.

Tosh: Jack, something Mary said. Probably the only honest thing she ever did say. I asked her why she gave it to me. She said after a while, it gets to you. It changes how you see people. How can I live with it?
Jack: There are some things we’re not supposed to know. You got a snapshot, nothing more.
Tosh: I don’t mean about Gwen and Ianto and Owen. I mean, the whole world.

Jack: How’s our friend there?
Owen: She’s dead.
Jack: Yeah, thanks, Quincy.

Quincy, M.E. was an American drama series that aired on NBC from 1976 to 1983. It starred Jack Klugman as an Los Angeles-based medical examiner who frequently investigated suspicious deaths.