Jason discards the battery from his phone to keep the military from tracking him with the signal. Yet later in the film, he receives a call on his phone without him ever getting a new battery.
The soldiers and Col. Jenkins try to hold off the spiders. Jenkins is using his handgun before he decides to use the heavy caliber gun. Before using the heavy caliber gun, he puts his handgun on the side leaving the holster on his right side empty. When he is taken down by a spider, the handgun is back in the holster.
The quarantined area shows 2 shops in the background. When Pete is on the phone, he's walking into what would be the quarantined area but now it has tons of foot traffic.
When Rachel and Jason are on the streets looking for each other and talking on their mind bile phones, they are actually on opposite ends of the block. There is an optical store that appears in both frames to show the scenes were filmed on the same block but different angles.
She pulls up behind a car whose tail lights are off, then on.
There is no Noble Street stop in the NYC Subway system. In addition, the sign saying "Noble Street" is not in the typeface that the NYC subway system uses.
Jason points out to Rachel that the rail is live with electricity and has to be avoided. In the same scene however, the rats are strolling along nicely on the live rail. But the live rail is only deadly if the person or animal is grounded (e.g., has one foot on the rail and one on the ground); the rats are not grounded. (It is the same reason that birds can perch on power lines.)
Doctor Stella identifies the eggs found in Jimmy as "insect eggs" and informs Jason that "some insects, such as spiders, plant their eggs in a foreign host." Spiders are not insects, a fact that a forensic pathologist would certainly know.
The couple Jason & Rachel Cole's daughters, despite being NY City residents, speak with the Eastern European accent where the Movie was shot.