Bats flew across some of the most stormy seas in the world to an icy wasteland their bodies were never equipped for, a 1000 km voyage at the very least, for the sole purpose of killing two minor research scientist. Birds are later shown to be affected by the defiant pupil: why wasn't it pelagic birds doing the killing instead? A couple of albatross could have done as much damage as those hundreds of bats. Alternately, penguins could have waddled inland and gone on the offensive, which would have been amazing.
The original novel only has mammals affected, so it's possible the show's writers were holding The Reveal that birds are also susceptible in reserve.
The bats are shown to be drawn to electricity. Exactly how much electricity was this small research outpost producing with its one solar panel?
Jamie loses her job in part because both her journalistic articles and her anonymous activist blog use the word "pettifoggery". Later, she's amazed to discover the fairly well-known fact that people tracking wild animals refer to their droppings as "scat". She's not presented as an out-of-touch character: why does she know the obscure word, but not the common one?
Probably because she's not an outdoorsy type, and has spent a lot more time writing stories about lawsuits than nature.
Seriously, why is there a kinkajou in New Brunswick?
In the Season Two finale, the Noah Objective is sabotaged in such a way that it sterilizes every human on Earth. The decade-later closing scene depicts an elementary school shutting down because there are no more children of an age to enroll. But the Noah Objective would never have been approved in the first place - not even by General Davies - if the technology to clone animals en masse didn't already exist at the time. So why hasn't that technology been used to produce a new generation of (gas-free, hence fertile) children ten years later?
Because even the thought of genetically engineering/cloning humans is expressly verboten. Only non-humans are fair game for "improvement" and "fixing" to be the way "they should be".
It's verboten now, when making humans the old-fashioned way is a ready option. Deprive us of the ability to reproduce conventionally, and taboos about human cloning will vanish as soon as the plummeting birth-rate stats are released to the public.
Also, wouldn't plenty of people who don't trust the various governments' intentions and/or competence have hidden away from the gas and thus remained fertile: able to reproduce themselves and donate gametes to others? The news was entirely open about the Noah plan, so it's not like the populace-at-large didn't know the gas was going to be unleashed, and the animal attacks have already destroyed many civilians' faith in the authorities' good intentions or ability to protect them.