When I saw him cutting his arm in the preview, I thought this was going to be the twist.
But he so clearly is not an android.

Caleb is not a robot, he is simply an idiot.

Just think about when they are talking about the Turing test, Nathan says it doesn't work unless the participant doesn't know that they are working with a robot. What if the test was about Nathan's consciousness, and seeing if he is actually thinking without knowing he is a robot?

beep that's a good theory but like someone else pointed out, you got the name of the company wrong. I think I actually would have preferred that ending.

It wouldn't be about outsmarting Ava: think about creating an AI that is so indistinguishable from humanity, that it can be emotionally manipulated by another AI? Wether that makes it the "lesser" or "greater" AI is up for debate, but to me it would definitely be a more impressive creation.

Caleb a robot??? But he showed extreme emotion and desperation
after being locked in. He would've had to have been EXTREMELY advanced for a robot to display such emotion. And if he was THAT advanced, he would've been able to outsmart Ava.

They didn't do a Bladerunner. Caleb has his own doubts, because of his past and suspicions about Nathan's abilities to manipulate, but we see that he is clearly no robot.

The fact that the helicopter comes back at the end proves that Caleb isn't a robot. Why would Nathan be setting Caleb free if he was just another one of his creations?

Nice theory, but I'm pretty sure the company was actually called Blue BOOK, not Blue Bell.

And also the start of the movie where he is sitting in the office.

Ok so what about his parents and the car accident?

I liked the fact that they didn't go for the twist because I'm sure many people were expecting it. And hey, we may still have been right but unless there's a sequel, we'll never know.