So-called "vampire" bats don't suck blood like vampires of legend. They inflict very small bites, mostly on sleeping animals, and then lap up the blood that oozes out. For Illya to have been seriously weakened by the bats in only a short time is almost impossible, and would have required an enormous number of very visible bite wounds.
About 38 minutes in the airborne view of the airliner shows no airline name, just Boeing 707. Clearly this is a Boeing corporate promotional film clip used as stock footage. Other times TWA planes are seen.
The "bats" swarming around Zark as he flees the lab are clearly just lengths of black crepe or fabric dropped from overhead like confetti.
Count Ladislaus Zark's plan is to use the bat's supposedly natural radar to interfere with an airport's radar and therefore make air travel impossible. The bats in question use echolocation, which is a form of sonar, not radar, and would be useless in Zark's plan.