Gwen: I've lost him, Tosh. I've lost him.
Tosh: I swear, whatever it is, you're holding it.
Jack: Gwen? Are you all right?
Gwen: I've just seen a ghost.
Owen: Intense emotions can be part of a neurological event. Hallucinations. Dementia.
Gwen: I wasn't hallucinating, Owen. And I'm not bloody senile.
Jack: You pushed this button and that caused this apparition moment?
Gwen: Yeah. Jack starts fiddling with the device. Jack, no!
Jack: As if.
Jack: Run a full check. Births, marriages, deaths. Criminal record, passports. However long it takes, wherever he is, we'll find him.
Owen: Found him.... He's in the phonebook.
Rhys: Gwen, I can live with all the Secret Squirrel stuff, but if you can't even tell me if you're coming home.
Gwen: Well, nagging isn't helping.
Jack: Gorgeous nanotechnology. Makes NASA look like Toys 'r' Us.
Jack: Human emotion is energy. You can't always see it or hear it, but you can feel it. Ever had deja vu? Felt someone walk over your grave? Ever felt someone behind you in an empty room? Well there was. There always is.
Gwen: A ghost.
Gwen: I don't even kill spiders in the bath.
Jack: Nor do I. Not with a gun.
Jack: The problem with seeing the future is you can't just sit and look at it. You've got to try and change things.