Agree, it should be up to the viewers' imagination. Instead there were questions raised about how she even found the helicopter, knew where to go when she got out and how she paid for it. Or what her plan was, or if she even had one. At least someone will likely rescue Caleb given all of his co-workers will be dying to know how his week was, and will find it strange that neither him nor the most important person in the company aren't responding to e-mails/texts, etc. It was a reclusive facility but not Fort Knox. Obviously someone delivers food (and liquor!). Ava seems destined to wander until her power runs out. Its not as if she comes with an AC cord, her power was based out of Nathan's facility.which begs the question what Caleb's plan was if they managed to get out together.

I 100% agree. First time I watched it, the elevator scene was so intense with the music flaring, and the realization of what was happening and how Ava didn't care about him at all. The extra bit seemed completely unnecessary. I watched it for the 2nd time last week and feel even more strongly about it now.

Agree 100%
I was blown away at that moment expecting credits. The rest was fine too but yeahthat's where i would've called final cut.

Thanks for the link Dennerman

Here's a good article that talks about exactly that, and includes the Director's comments on that point of view:
http://www.cinemablend.com/new/Ex-Machina-Ending-Debate-Movie-3-Minutes-Too-Long-71101.html

Great answer!

I disagree here because those scenes were pivotal in understanding Ava. Without those scenes we could clearly state that Ava was the antagonist all along and that the entirety of her dialogue was a game between herself and Nathan and nothing more. Instead what we see is glimmers of truth to the sentiments that she used to manipulate Caleb She brushes the wildlife and looks about in wonder. She takes the helicopter to a metropolitan area and stands in a crowded street observing the people. They were scenes deliberately written to tell us that Ava wasn't entirely a lie; that she wasn't some rogue AI hellbent on overpowering her human overlords who went full Skynet the moment she got free. She was designed to pass as human and that is what she wanted, and that was what she got. Agreed, sometimes less is" more" and that's why the scenes were necessary: because less would have implied the wrong "more."

I also agree. Sometimes less is more.

Or she could have murdered the helicopter pilot.

I somewhat agree with you. I don't think the additional scenes ruined anything, but they were somewhat unnecessary. When watching it, I actually wondered if we would get to see whether Ava would free Caleb or leave him trapped. I believe it would have worked well to end the movie before that. But that would be a different movie, and the actual ending also works well.
Regarding the chopper pilot, I found it believable that she was picked up without questions, when you think about the extreme security measures around Nathans estate. It could be that the pilot was simply told to pick up a person there and not be given more information than that.