Will's M16 runs out of bullets and there are several clicks as he supposedly tries to fire more rounds. M16s lock open on the empty magazine, so there wouldn't be any clicking.
On the computer screen, the word "Courir" can be seen on a button. It is a literal translation of the word "Run" in french, but "courir" means to run (on your feet). This shows that it is definitely not a "real" operating system, since it would be written "Exécuter" instead.