Just before the Doctor enters the TARDIS near the end of this episode, three children see him. When River is examining the files in the future, she has photographs of the children shown at the moment they met the Doctor but there were no cameras around to take those precise photos.
Trivia: This makes the first televised appearance of a Cybermat in thirty-six years. They were last seen on-screen in the 1975 serial "Revenge of the Cyberman." The Cybermat's appearance here is closer to its very first appearance in "The Tomb of the Cyberman," rather than the sleeker (and primarily CGI) design of "Revenge."
The Doctor: Oh, you've redecorated. I don't like it.
Craig: It's a different house. We moved.
The Doctor: Yes, that's it.
Craig: Doctor, what are you doing here?
The Doctor: Social call. Thought about time I'd try one out.
Craig: I can't cope on my own with him. I can't... he just cries all the time. I mean, do they have off switches?
The Doctor: Human beings. No, I've checked.
Craig: No, babies.
The Doctor: Same difference.
The Doctor: So what did you call him? Will I blush?
Craig: No, we didn't call him "The Doctor."
The Doctor: No, I didn't think you would.
Craig: He's called Alfie. What are you doing here, anyway?
The Doctor: Yes, he doesn't like Alfie. Personally he prefers to be called "Stormageddon, Dark Lord of All."
Craig: Sorry, what?
The Doctor: That's what he calls himself.
Craig: And how'd you know that?
The Doctor: I speak Baby.
Craig: Of course you do.
The Doctor: Craig!
Craig: What the hell are you doing here?
The Doctor: Oh, I'm the Doctor, I work in a shop now. Here to help. Look, they gave me a badge with my name on, in case I forget who I am. Very thoughtful, as that does happen.
The Doctor: You look awful.
Craig: (about his baby) I haven't slept, have I? I still can't stop him crying. I even tried singing to him last night.
The Doctor: Yeah, he did mention that... he thought you were crying, too.
The Doctor: Craig, take Alfie and go home.
The Doctor: No?
Craig: No. I remember from last time, people got killed. People that didn't know you. I know where it's safest for me and Alfie, and that's right next to you.
The Doctor: Is that so?
Craig: Yeah, you always win, you always survive.
The Doctor: Those were the days.
Craig: Where am I investigating?
The Doctor: Well, look around. Ask questions. People like it when you're with a baby. Babies are sweet. People talk to you. That's why I usually take a human with me.
Craig: So I'm your baby?
The Doctor: You're my baby.
Craig: Doctor, listen to me. If the Cybermen are here, then we're not safe. We've got to go. We got to go back to base.
The Doctor: We've got a base? When did we get a base?
Craig: I'm going down to the shop. We're out of milk. You know what to do if he cries.
The Doctor: No!
Craig: Me neither!
The Doctor: (to baby Alfie) Your dad's trying his best, you know. Yes, I know it's not his fault he doesn't have mammary glands. No, neither do I.
The Doctor: I'm the Doctor. I was here to help, and you are very, very welcome.
Craig: The Cybermen. They blew up. I blew 'em up with love!
The Doctor: No, that's impossible. And also grossly sentimental and over-simplistic. You destroyed them because of the deeply-ingrained hereditary human trait to protect one's own genes, which in turn triggered a... uh... uh... yeah. Love.
Craig: Like a--like a "beam me up" teleport like you see in Star Trek.
Referencing the popular American TV franchise Star Trek where the characters are typically "beamed" to and from their ship using a "transporter." A famous line being, "Beam me up/down, Scotty," Scotty being the Chief Engineer in the original series and typically the ranking officer handling the transporter in times of emergency.