When the TARDIS arrives at the end of the episode, the Doctor's severed hand starts to glow, as the TARDIS key did in the 2005 Doctor Who episode "Father's Day".

Rhys Williams: You know, it's rude to stare.
Gwen: I thought telepathy would get you to make me a cuppa.
Rhys Williams: What's it worth?
Gwen: What do you want?
Rhys Williams: I'll draw you a diagram, shall I?

Jack: The cracks in time trace back here to the Rift. This city, this Hub, is the centre. What you’re seeing are ripples and aftershocks. The Rift is splintering because of you.
Owen: What?
Jack: You opened the Rift without knowing what you were doing. You’ve caused the temporal cracks to widen. Time is seeping through.
Owen: If it wasn’t for me, you two would still be in the 1940s. So are we going to sit around crying into our lattes, or are we are going to do something about it?

Jack: So he was on his way there, time splintered and he ends up here.
Andy: Excuse me? Hi. Any time you feel like talking sense…
Jack: That soldier came through a crack in time
Andy: He’s not serious, is he? This sort of thing just doesn’t happen. Not in Cardiff.
Jack: Just because you can’t understand it, doesn’t mean it isn’t true.

Jack: Under any other circumstances, an exuberant Roman soldier would be my idea of a perfect morning.

Andy: Everyone's saying it, you know. Word on the streets. Do you think this is the end of the world?
Gwen: Oh, Andy, don’t be silly. Do you think the world’s going to end on your shift?
Andy: I’ve seen you use that smile on a lot of people.
Gwen: What smile?
Andy: The smile you use to reassure people when, deep down, you know everything’s gone to shit.

Owen: People are dropping through time and they are gonna bring every disease in history through your doors. So you'd better be ready.
Tosh: Owen.
Owen: You scared enough yet? 'Cause fuck knows I am!

Owen: Who the fuck are you anyway, Jack Harkness? You don’t even exist. We’ve looked. So if you’re not even a real person, then why the hell should I follow your orders?
Jack: Get out.

Jack: You're a united front now, Toshiko, the poor girl who'll screw any passing alien that gives her a pendant. Owen, so strong he gets in a cage with a Weevil, desperate to be mauled. Ianto, hiding his cyber-girlfriend in the basement. Your three comrades here pumped bullets into her, remember?
Gwen: I've got to get Rhys back.
Jack: Yeah, 'cause you're so in love with Rhys that you spend half your time in Owen's bed.
(Gwen punches him)
Gwen: Fuck you!

Owen: Stay down!
Jack: You wanna be in charge, Owen? You’ve got to have significantly bigger balls.

Bilis Manger: From out of the darkness, he is come.
Gwen: What is he talking about?
Bilis Manger: Son of the Great Beast, cast out before time, chained in rock and imprisoned beneath the Rift.
Gwen: What?
Bilis Manger: All hail Abaddon, the Great Devourer, come to feast on life! (Abaddon emerges) The whole world shall die beneath his shadow.

Gwen: The visions we had. We all saw people we loved. What did you see?
Jack: Nothing. There was nothing.
Gwen: Jack, what would have tempted you? What visions would've convinced you to open the Rift?
Jack: The right kind of doctor.

Owen: What’s the matter?
Gwen: He was just here. Something’s taken him. Jack’s gone.

As confirmed on the DVD commentary, when Owen turns and leaves, you can see the script pages poking out of his back right pocket.

This episode is a prelude/lead-in to the Doctor Who episode "Utopia (1)". However, in that episode, the TARDIS materialises on the plaza and Jack runs to meet it. Here, he's inside the Hub, the TARDIS seemingly materialises inside the Hub with Jack (the noise, the rushing wind), and he departs immediately.