There is a 'A v P' website with trailer, competitions and assorted other things:
http://www.avp-movie.com/us/html/aboutfilm.html
I think they are going to explain the timeline inconsistency by having them visit an ancient tomb buried under the Antarctic ice. I'm guessing that these Aliens visited Earth a few million years ago, had a run in with Tyrannosaurus Rex and never came back again.