What does an alien do once he has completed his mission on earth and ready to go back home?

I've heard the rumour that Earth is a spaceship. Keeping that remote possibility in mind....

If your purpose on this magnificent spinning ship is complete, then enjoy the days ahead. It's all relaxation, sunshine and happy from here on.

He/she could go to Venice Beach, CA.

Half the people there look alien any way. E.T. would blend right in, and probably like it. He may decide to stay forever... Hey, maybe that's where those folks come from!

Honestly speaking and to be frank with you, I am cursing my fate why I am not getting such good enlightenment soon. I am also honestly, sincerely and earnestly praying with implicit faith, unshakable belief and unflinching devotion. Still I am very hopeful. Can you also please afford to wait till I get some creative ideas about this.

Seems to me if they're smart enough to have a spaceship, they're probably smart enough to have a way to contact it.

They do this thing called "Holobobing" where they take on the role of a human being. Obama looks a little shifty to me...

the ship is always near

They would have to find a way to remain at their pick up site, but not be detected.