None of the characters seem to have any issues with their hearing despite being in a cramped enclosed space with lots of gunfire and grenades.
A character throws a grenade down a shaft and it explodes into a large fireball. Fragmentation grenades don't have a fire explosion.
At around 23 minutes in, the Marcus Longridge character states the following, referring to his MP5: "Well, it's a rifle, actually". The MP5 sub-machine gun used by himself and the Shirley Dander character are not in fact rifles, but rather, pistol-caliber sub-machine guns.
At around 11 minutes, the enemy agent slips on the stairs and catches his left hand on a blade placed on the banister. Although, it might be safe for Lamb to think the agent would be holding a gun, he wouldn't take it for granted that the agent would be right-handed.