When Michael gets into KITT after the Lynx disguise melts off, the car hood is covered with beads of moisture. As KITT sighed off seconds later, the moisture is gone.
The plot hinges upon the bringing of a biological weapon into an embassy within the U.S.A. Weapons of mass destruction such as biological weapons would violate the conditions for the existence of such an embassy; further, a diplomatic courier would not be immune to being searched if such a weapon were being transported by him.