This isn't disney dude.

the crazy woman actor
I find the idea of the woman being an actor to be hugely problematicit would mean that Howard was trusting that the female actor wouldn't let anyone know what she'd done.
Surely if Howard had just kidnapped Michelle, her picture would be on the news. Being complicit in that kidnapping would make that actress an accessory to a crime. Howard would have to be confident that in his time in the bunker she wouldn't spill.
The only thing I'd be okay with, weirdly, would be if the woman was Howard's wife. Like she agrees to help him kidnap and keep this other woman because it would mean that he would be staying away from her and her daughter. (Though that assumes Howard would prefer the company of a kidnap victim to the company of his own daughterthough maybe in this scenario Howard doesn't even have a real daughter or the real daughter is dead or something?). There would have to be something more than money or simple blackmail for a person to be complicit in such a kidnapping, in my opinion, and more of a reason for Howard to trust her.
Imagine Michelle emerging from the bunker, taking the hazmat off (no poisoned air), and stumbling to the nearest house for help, only to find the "crazy woman" and Howard's daughter sitting down to a normal breakfast.
Frankly, though, like I've said before, I think that the tension of the movie only really works if you know that the aliens are real. There has to be that push-pull of knowing that Michelle is in danger in the bunker (duh!) but also would be in danger outside of the bunker.
While it isn't as good of a movie (directing, writing, or acting-wise), there is a movie called
Saving Grace
with a very similar premise (guy holding woman hostage claiming to be keeping her safe from apocalyptic attack) that I felt like handled the ending dynamics in a better overall way and also balanced the ambiguity of what was happening a little better.

lemme clean it up
it should end with her taking the mask off and hearing the sounds of the world continue to roll
and possibly you can have a shot of fake blood to stage the crazy woman actor
EHHH EHHH

That is such a boring and cliche is idea. No offence but that's exactly why you're not a writer and instead just writing stuff about the film on IMDb.

There's a lot of examples of overbearing girl-power in movies. This isn't one of them. Just because the protagonist is a woman doesn't mean it's feminist. At no point is she out wrestling men or doing anything a woman could not do. Quite the opposite. There are multiple scenes where Howard physically dominated her. She outsmarts him in the end, but he got the better of her several times in the movie.

I agree. I think when she stands on top the truck, and sees the alien spaceship in the background over the corn field would have been a better place to end it.
They should have ended the movie like they started it in an open ended way just leaving it open after she sees the aliens, and realizes it was all true.

I almost always read a movie's synopsis when i'm gonna watch one.. and i'm very grateful i didnt do it this time.. i rated it 8/10..
Having that said, the movie shouldve ended when she saw an airborne alien with tentacles going towards her and said "come on".. lol

Disagree with OP.
If the film ended there then it would be a cliche. A hollywood crap.
This ending is a true twist and an original idea.

http://www.imdb.com/mymovies/list?l=15227539

The last twist really ruined everything they had done up until that point. It was a claustrophobic thriller for 90mins, then a sci fi action flick for the last 10. What the hell were they thinking.

I haven't seen
Signs
, but my main memory of when it came out is how irritated people were by the ending.

All good points and I'd agree on everything. The last ten minutes just felt like they'd ripped off War Of The Worlds and tried to pay off audiences who liked the Cloverfield universe. Knowing JJ Abrams, I was prepared for some kind of left-field link to the original movie.
Do you remember Signs? I really thought the twist would be that there were no aliens and the threat outside the house was something completely different. I was most disappointed by the ending on that one too.

I enjoyed the bunker, mystery solving (who was the girl in the photo), making the suit, etc. Once she got outside, it dropped the ball.
I enjoyed the cognitive dissonance that the real existence of the aliens presented.
As a person (and specifically a woman) I totally understood where Michelle was coming from. You wake up chained to some random dude's wall and he tells you that you need to spend the next TWO YEARS with him in order to stay safe? On a human level I was like "Yes, knock him over the head, grab those keys, and get yourself OUT OF THERE!".
But as a viewer (and given the Cloverfield name), I just knew that the alien attack was going to be real. So at the same time that one part of me wanted her to get out of the bunker by any means necessary, another part of me knew that escaping could/would be fatal. I always think there's something really powerful when a character in a horror movie is doing exactly what you'd do in their position, and yet as a viewer you know it's the wrong action.
I also liked the irony that having to harden her resolve and go for broke in order to escape from Howard is likely what gives her the nerve at the end to face her fears and attack the alien. Had Michelle from the beginning of the movie been picked up by the alien, she would have been toast. Facing down a human monster prepares her to take on an inhuman one.
Could the movie have been just as good without the alien part at the end? Definitely yes. With a few tweaks there could have been no threat or a non-alien threat and the movie could have still worked (though, again, I like the jarring nature of knowing that Howard was a monster and also a savior).
Do the aliens add anything to the story? I mean, I think so in a thematic sense. A much more rote ending would be if she like went back to an abusive boyfriend/husband and punched him in the face or something. Horror/thriller/action movies often have that moment where the formerly meek character stands up to a bully from the beginning. I kind of liked that the movie went really big instead of just showing Michelle emerging from her experience and being more assertive in her relationship or something.
The bunker dynamic (and in particular the three central performances) is undoubtedly the strength, but I don't find that the alien element derails it.

I tend to agree. The bunker dynamic was much more effective, even if there was a genuine threat of some description outside. The souped up alien ending totally jarred with the subtle tension that had gone before.
I wondered if he'd mutilated the pigs himself; also, they could have done something with the woman outside to make it more ambiguous. For example, made her injuries look like a car accident - she was asking for medical attention rather than refuge?
I enjoyed the bunker, mystery solving (who was the girl in the photo), making the suit, etc. Once she got outside, it dropped the ball. Perhaps they tried too hard to make it a "blood relative" to Cloverfield, though there doesn't seem to be much connection. Unless the aliens are looking for their lost alien boy who was last seen trashing Manhattan?

It should have ended right after she said "Oh, come on."
RIGHT!!!!

It should have ended right after she said "Oh, come on."

As soon as it went to aliens it lost all its credibility. It was a good mystery what happened on the outside, did he kill his daughter and abduct another to replace her(that wasn't even explained well or at all) but once aliens came into the picture I got angry

So if I was a guy that starred and survived the film, it would be fine?
Ok..

That would have made it a much better movie, no question!

Why should she go back to her boyfriend? It's heavily implied that he was physically abusive.
This whole film was feminist as beep. Amazing. Too bad it's lost on audiences with penises.

The latter. It seemed legit eerie and creepy up until that point, like what could possibly be going on out there? The sci-fi aspect was a cop-out imho.

Can I ask you: were you expecting that ending?
Because of the Cloverfield name in the title, I was 99% sure that it was going to be alienswith only a few wavering moments of doubt.
Maybe the "gear shift" into sci-fi at the end didn't bother me as much because I was so expecting it. Were you expecting it and let down by it? Or not expecting it and unimpressed with the way that the movie moved from one mode (thriller) to another (sci-fi/action)?

I don't mind the
aliens are for real
ending, but it was done poorly.

It was all a set-up. What with the whole ready-made bunker thing, this guy is clearly a seasoned pro at making his victims believe a chemical holocaust is happening outside.
I'll admit that I'd considered in the beginning that maybe he'd mutilated the pigs himself. But the woman? That would mean he'd hired an actor or had someone in his life willing to play that part. That was actually the moment when I became pretty sure the attack was real and not being staged by Howard.
You raise the point that maybe Howard had pulled an "apocalypse scam" on Brittany (the earlier victim), something I had not considered. I figured he had just straight-up kidnapped her.
Because reality just happens to be "pro-male" - men are simply more powerful than women. Movies are obviously not reality, but in situations when even a man is obviously incapable of superhuman power to overcome their captors, using a woman instead is really pushing it - and clearly has some overarching agenda.
But Michelle never physically dominates Howard in a fist-fight or anything. Her escape is a mix of taking him by surprise and then luck. She runs away from him and then tips over the barrel of acid. People who are desperate are capable of surprising feats of strength/agility. And despite his strength, Howard is not exactly in prime physical shapeI can believe that a woman could run away from him. I would not have believed Michelle punching him out or putting him in a choke-hold or something.
agenda
What agenda? A man kidnaps a woman for his own purposes (something that happens in real life, unfortunately). She manages to escape (rare, but not unheard of:
http://q13fox.com/2015/02/04/sheriff-woman-escapes-kidnapper-when-his-car-gets-stuck-in-mud/
). I just don't see how your ending is less "feminist"because you say you'd include up to the part where she takes off the gas maskwhich is after she escapes from/kills Howard. So would your version be less feminist because she'd go back and reconcile with her boyfriend?
The idea that the movie is some sort of pro-woman propaganda is just kind of baffling to me. If the movie was truly arguing that women are unassailable fonts of awesomeness, then you wouldn't have the death of Brittany. Michelle gets lucky at several pointsI think it's pretty clear in the movie that a lot of her survival is down to luck, not some inherent "woman power".

@morph85 The only thing I'd add to your reply is a mic drop.