In level "Low Life" the player is trying to reach the surface via an underground parking lot. At level P5 antlions attack from underground burrows. However level P5 is not the ground floor. Under P5 is P6.
Grammar mistakes in subtitles.
The ammunition icon for the MP7 submachine gun is that of rifle ammunition. In reality the MP7 submachine gun fires 9mm pistol ammunition.
The ammunition for each weapon should be a multiple of the maximum ammunition that can be held within a magazine.
The drums marked 'Flammable' are explosive and not flammable.
Weapons sometimes reload themselves if unequipped.