Let me start by saying, I didn't hate the movie. It's obvious that some of the story didn't make the theatrical release, so I suspect we'll see a longer, better version in the DVD release.
That said, nothing will fix the middle. Nothing. Case in point, the biologist and the geologist...or (as we should think of them forever) the redshirt and the other redshirt. They were not hapless victims who will be mourned as real people caught in the wrong place at the wrong time, but a storytelling setup so weak that it threatened the integrity of the whole. Did I know they would die from the moment they first appeared? Yes. Sadly. I didn't want to know that those two guys would be dead by the end. I didn't want to believe that their character introductions simply screamed 'target painted on their chests', but unfortunately the writing was on the wall. It was obvious that they were doomed. A geologist that can't just simply say 'hello' back but has to be confrontational at the drop of a hat. A biologist that is openly friendly and goofy. DEAD.
Getting back to my point. Let's start by examining the way team communications should work. The team starts out in constant communication with the ship, which is the kind of protocol I would demand if I was monitoring the team from the safety of the ship. Everyone online all the time. Any loss of communication and I'd yank that team out. No questions asked. You stay in communication or you don't get to come on a mission years out into space again. Ever.
That's the very way that the expedition team started out as they explored the underground and unknown complex, and then...they split up. It was suddenly Shaggy and Scooby on their own.
What captain, team leader or just plain everyday person worth their salt splits up on a planet containing only 17 crew members facing the unknown?
Worse than this, and for reasons never explained, the biologist and the geologist got lost. The place is mapped for them in 3D...and they got lost. They geologist himself mapped the place...and they got lost. They're in uninterrupted communication with the team underground and the ship...and they got lost. The ship was monitoring all of them on camera and radio...and they got lost. They wandered down a few corridors traveling in very set directions...and they got lost. They could have called anyone at anytime and asked for directions...and they got lost. They heard the warning that they had to get back to the ship ahead of the storm...and they got lost. Did they forget how to call the ship (what with only one ship they could call)? Did the ship forget them (because 17 people are too hard to monitor)? Did the team forget them? Doesn't matter. They got lost.
Then, despite the unexplainable reasons for them getting lost, the crew on the ship decided to abandon them. They didn't leave a guy on the bridge to monitor their safety, no matter how tenuous the communication might have been. They simply wished them luck and abandoned them with no more concern than two guys who missed a connecting bus. This plotless decision, which is soundly outside the realm of good judgment, is a turning point for me in the film.
Years from Earth. One ship. Only seventeen people. An endless amount of things that can go wrong on and off the ship. Abandon two people to the dark unknown with no communication whatsoever like they're camping in the backyard.
Then, my ultimate pet peeve rears its ugly head. Extreme character contradictions for the sake of artificial tension.
The biologist and geologist were soundly against going anywhere near an unknown life form. They purposely went East to avoid the 'life form' detected to the West. And who wouldn't? Alone on an alien planet in alien ruins surrounded by alien dead ANNNND cut off from the ship both in terms of distance and by communication. I'd go East. Can I see a show of hands of anyone who'd go West without sufficient safeguards while lost underground in the dark and subsisting on canned air?
Then...
...they got caught in the room of oozing pots and the giant head and a freakish, faceless, albino snake slithered right up to them to say 'hello'.
Suddenly, the biologist wanted nothing more than to give a large glistening, slithering, tentacle worm a hug. The hell...? Did his healthy respect for the unknown, and therefore potentially dangerous, go right out the window in a place with no windows? There are insects no larger than a freckle that can pass diseases to you and me on Earth, but this guy reached out to a tentacle in a posturing stance that just screamed dangerous. Had this 'biologist' never seen a cobra, timber snake, rattler, or any other creature I could name demonstrate predatory posturing? Never mind that it had no eyes and nothing that would have communicated 'safe to touch'. Never mind that it came right up to him, which is generally a sign of fearless disdain or hostility in an animal sense. Never mind that he had NO IDEA WHAT IT WAS! It could have been as harmless as an earthworm, but it was the size of a vacuum hose! How thin was the air in his helmet that he would suddenly switch from his 'East not West' policy? The geologist was stuck in a helmet choked with hash, but the biologist was...what? Bipolar in his respect for the unknown? Selectively careless in the case of alien cave snakes?
As a side note, if you should ever find yourself alone in the wilderness, whether underground or in the full, bright, happy light of day and a snake comes up to you, move away. If a snake moves away from you, you're golden. If it comes up to you, MOVE AWAY. You may also hit it with a stick if you have to, but do not attempt to hand feed it or it will feed on your hand.
That scene was so B movie that it can't be fixed. There is no director's cut that will fix the tragic 'Laurel and Hardy meet the Mutant Zombie Worm' scene. It can't be fixed. It can't be explained away.
The scene would have made more sense if first, they're entrapment in the complex was explained by an accident or a brush with technology that kept them from leaving, and second, if they had fled from the snake only to be pursued and killed. It would have been more terrifying. It would have made sense. It would have been realistic.
Instead, they reduced two space faring scientists in a Ridley Scott sci-fi film to two teenage stoners in a slasher flick. Done. Dead. Can't be fixed.