Also the deal with Tarek and the glasses was just so hokey and I couldn't suspend my disbelief with that silly stuff.
The guards are supposed to act like guards and the prisoners treating everything like a joke will just incite them, so I found that to be very stupid. If you volunteer for something like this, why would you treat it as a joke? You were specifically told that it's supposed to be real. I don't know what it was, I just felt that everyone treating the experiment as a joke (at first) came across poorly. I know of the Stanford Prison Experiment, which this movie is inspired by, and I thought that it would make a great movie if it was done right and for a while there I was really hating this movie, just hating it.