Just saw it... A few comments (SPOILERS)

So I just watched this last night. As a huge fan of French horror, I was really excited for this. It did not disappoint, but a couple of things left me questioning a few plot elements:

What exactly was Frank's strategy in throwing that gas grenade in the library? I mean, how dumb can you be to purposefully limit your own visibility in tight quarters? That just made no sense. Then he was surprised when he heard the mutants running around him and he couldn't fire upon them...

Secondly, also about Frank, why did he just let his girlfriend die? I mean at first I thought, "Oh, he just thinks she's one of the mutants..." But he clearly sees she's fine and not infected and he just watches her die. No more BJs for you Frank.

At the end when Sonia emerges from that tunnel into that enclosed area, she looks around in despair when she realizes it's all protected with barbed wire and she cannot open the fence door. I mean really? If cannibalistic mutants were chasing you, barbed wire would stop you from escaping? She's a medic for chrissakes, she could just take a couple of gashes from the wire and tend to those wounds. HOWEVER - it ended up being a good thing she didn't leave because she would have ran into a massive group of mutants. So I guess that's ok.

Also in that same scene, you're telling me that the mutants can break down a locked door if they smash it enough times, but a little barbed wire can hold one of them down indefinitely? Again, that was just too much of a suspension of disbelief for me. Instead, why didn't they have Sonia push him onto a stray piece of sharp metal so he gets impaled, or something similar. Then it's believable. But nooooo, barbed wire around the arms can hold this raving lunatic at bay. Come on.

Also in that scene, the military fire upon the hordes of mutants and narrowly miss Sonia a number of times... dumb. She's obviously extremely valuable (a person with vast medical knowledge when survivors are few and far between would be invaluable). Why wouldn't they just touch the copter down and pick off the mutants instead of risking her life with stray machine gun fire?

Another thing: everyone in this movie had this problem where they loved watching other people die. I mean, rarely does anyone make any attempt to help others when those others are being mauled by a mutant. Sonia especially loves to watch others die. Then I thought, "If she fires, the blood will infect the one being attacked." I guess that explains it. But still, she watches a number of people die for no reason.

All of these things might make it seem like I hated the movie, but despite them, I still enjoyed it and give it a 7. It was pretty crazy, and had some good gore. Any ideas on the above questions would be appreciated.