The subtitles are poorly timed.
The bars on the door to the Machinery Room in Mission 2 do not actually prevent the door from opening.
It is possible to open doors without guards noticing even if they are looking right at them.
When the Player unscrews a grate, he always unscrews it to the left. On the opposite side, they should unscrew to the right.
There is no logic to the placement of many of the loot items.