They never did, because technically, it never happened in our world. People are returned to the exact time they're taken, and without memories of the city, so no matter what happens here, it's as if we never left.

[How should she put this... Because now, with her experience, she doubts that there are things that would affect their home while they're here.]

Forget everything you know about our world-- the gates, the paradoxes, time itself. Anything can happen here, because this world operates on its own rules.

... We are only here as guests.