how do we know that was earth?
I thought it was an experiment gone wrong.That's why they dropped him off-just in case.
also,the aliens were different.why? the young ones seemed the same,so where were the adults?..and the black liquid that turns into an alien? a little too loose of storytelling.smart storytelling-no.more like their rabid fans had to have another alien movie,but it's played out,so they went in a different direction,still trying to tie it all in....w/no answers,they keep you wondering,therefore still interested.