Alien Experience were lucky enough to interview co-director Greg Strause. It’s a really interesting and in-depth interview that covers lots of aspects in the film. Here’s the most interesting points:
-Some new additional scenes were shot. Greg hints that the Predator homeworld will be seen in the movie. There’s also some new scenes at the beginning of the film.
-There’s a scene at the end that ‘bridges’ AvPR with the first Alien film. It shows how human technology will have advanced so much so I’m guessing some of the Predator technology gets left behind on Earth.
-The Predator net gun doesn’t appear in the film but he does have a new armoured ‘Glove’ weapon. It’s unfolding armour that encases his hand allowing him to punch through concrete etc.
-The facehuggers are darker and slightly different, like ‘Warrior’ facehuggers. This apparently explains why the aliens have ridged heads. There’s also a big Facehugger attack in the sewer at some point in the movie.
Check out the rest on Alien Experience. There’s also three new pictures plus two behind the scenes shots which I’ll post in a moment.
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there was already different syles of eggs to beggin with... the translucent ones in "Alien" and the completely opaque ones in the newer films... the alien in the first one also had a "white-ish" head dome too...besides.. their concept of having the alien adapt it's shape to the surrounding enviromnent makes more sense than your giving it credit for 
but here's an explanation that fits with your guys concept of "canon": The "warrior" eggs belong to those in an already well estabilished hive (like in Aliens) and not to those in a non completely well estabilished "hive" like in Alien Resurrection.. why were those aliens not ridge headed? They had more than a few days growth 
I'm really starting to think Anderson should've been pegged for the directorial role for AVP2, but this time, cut the damn man loose, Fox. Don't freak'n bound and gag him with what can & can't be done. I only hope the movie redeem's itself once it's released, but what with certain facts about it already having been disclosed (specifically pertaining to both the Aliens & Predators), I'm really starting to doubt it. There's so many off the wall notions, comments & ideas from Greg in this interview, I'm not even sure where to begin on an analysis and explanation of what, how & why it's soooooooo wrong. 
