Patzer

Throughout the series characters are shown firing multiple long bursts of automatic fire from their rifles without reloading. For one thing a trained and experienced solider rarely fires in this manner, it wastes ammo and makes recoil hard to control, they fire in short three to four round bursts. Second the rifle most commonly used by the Nathan James crew is the M4 carbine, which has an automatic fire rate of 700-900 rounds per minute (depending on exact model), they carry standard 30-round magazines, in full auto mode it would fire all 30 rounds in 2.5 seconds.

The series makes frequent use of the Hollywood myth that a gun equipped with a silencer is almost totally silent, with guns making a quiet popping sound with people only several feet away not hearing a thing. However silencers aren't nearly this effective, in fact "silencer" is just a made-up laymen's term, they are actually called a suppressor. Gunshots are extremely loud, especially the 5.56x45mm M4 rifles used by the military (and on this series), which are 170 decibels (dBP), by comparison a jet taking off is 140-150 dBP. A suppressor reduces the sound of an M4 to about 120 dBP, which is certainly much quieter than 170 dBP (about 8x quieter in fact), but 120 dBP is still pretty loud, equivalent to a chainsaw. Even the sound the bolt makes when cycling is loud, about 110 dBP, roughly equal to a lawnmower.

There is a missing explanation on the need for the primordial strain. Like most mutations, they were random and various, resulting is possibly 1000's or even millions of different variants. By some chance (or perhaps by design) this process halted. Their only hope was to return to the original strain for a cure/vaccine and hope that it would be able to work with all of the mutations.