In Ex Machina, towards the end of the movie, we see Caleb hacking the system of the building to reverse the door mechanisim, and if you pause the movie at the right time, you could see that he is writing in a language not too different than C++ or Swift.
The code he writes is a function that finds prime numbers. Not sure what that has anything to do with hacking the system, but for the sake of argument, we will assume it is required by a complex function within the hacking procedure.
What really caught my attention was the comments he wrote before the function declaration. I know the comments are supposed to describe what the next bit of code is intendded for, and I know that the written comments have nothing to do with finding prime numbers, as expected because they are meant for the movie audience to let them know that he is writing some hacking code.
However, a hacker would never leave evidence of his "crime". Meaning: he would not write any comments that would give away his intentions, and second: he does not have time to write comments. The only reason someone might want to leave comments in code, is if they are expecting someone else to read the code later and be able to modify the code (enhance, update, etc). Neither of which is the case in Caleb's situation.
So why did Caleb leave comments in his "hacking code"?