Dr. Lu is talking to Sophia about virus mutation and states that the bird flu becomes H1N1. That is incorrect H5N1 is commonly known as the Bird Flu, and H1N1 refers to the Swine Flu.
Spanish flu did not kill 20% of the world's population in 1918. The global mortality rate from the 1918/1919 pandemic is not known, but an estimated 10% to 20% of those who were infected died. With about a third of the world population infected, this case-fatality ratio means 3% to 6% of the entire global population died.
The stewardess connects the virus dispenser to a copper line on the air handler. Doing so would only introduce the virus into a closed loop refrigeration system. It would not introduce the virus into the air being circulated through the mall. To do so, the virus would need to be introduced via an air return duct. The units on the roof are condensers and do not involve any air flowing into or out of the mall.