FAQ for
A.I. Artificial Intelligence (2001) More at IMDbPro »Artificial Intelligence: AI (original title)

When the film first came out, it was assumed that the beings seen after David and Teddy have been frozen were aliens. They are actually future mecha, seeming to fulfill Gigolo Joe's words that when the end came, the mecha would still survive after human beings had died out ("They made us too smart, too quick, and too many. We are suffering for the mistakes they made because when the end comes, all that will be left is us."). This becomes obvious when watching the film a second time, since the voice of the chief mecha is the same voice in the beginning - the actor Ben Kingsley.

The future mecha, much like human beings, are in a search for information regarding their past, which is why David is such a perfect specimen for them to find, given he lived among humans and his mind is filled with their interactions.