The first idea for this movie dates back to 2000. It originally had Burt Reynolds wanted as an actor in the film. It also was meant to be theatrical.
Originally, people who become infected would transform into the giant bird-like monsters. However, the budget did not support any good transformation special effects, so the idea was scrapped.
Sutures during the surgery scene are too far apart. The wound would have also been thoroughly irrigated prior to suturing. As a result, there would have not been a foreign body present after wound closure had begun.
The blood transfusion during the surgery scene is not infusing, which is probably a good thing as there is enough air in the IV tubing to cause an air emboli and actually kill the patient.
At 17:44, there is an Establishment Shot outside the Hospital with a bunch of extras walking into, walking out of, and standing around the Hospital. At 30:46, in an obvious recycled scene, there is a second Establishment Shot with all the same extras doing all the same motions.