In the comic series, the aliens acidic blood loses its acidity once the creature is killed. I think that's why those holes are there. I also saw that hole with the artic wear. I told my buddy while we were watching it that they couldn't survive that climate with that little on.

I had my own ideas about concepts for the movie. I even concidered writing my own script back in the early and mid nineties(sp?) . I might just write it now for skill honing now that it's been done. Same with Alien 3 and 4. Alot could have been done differently if only you scraped the stories.