how do you say "when did the world end? can we go home now" in japanese?

Answer 1

(-: I don't think anybody will have any clue what you mean, but my Japanese husband says:

"Kono yo ga owatta no wa itsu desu ka? Moo, kaette ii kai?"

Good luck. Confusion to the masses!!!

Answer 2

I would make the translation a little more dramatic and less polite than the other poster's, since this kind of phrase would only comes from some kind of climax in a SF story (or a SF comic).

when did the world end? --> 世界は、いつ終わったんだ？(Sekai-wa itsu owattanda?)
can we go home now? --> もう家に 帰って いいのか？(mou uchini kaette iinoka?)