The use of stadium flip-cards as an analogy for a terrorist cell also refers to something now known as Great Rose Bowl Hoax. In the 1961 Rose Bowl game the Washington State Huskies played the Minnesota Golden Gophers; a halftime card display by Washington was supposed to end by spelling out "Huskies" and "Washington" and an American flag. A group of Caltech students substituted an altered set of instructions before the game, with the end result that the word "HUSKIES" was spelled backwards, and the next display spelled out "CALTECH" (the final image of the flag never showed). This image was broadcast to an estimated 30,000,000 TV sets across the country, ensuring its notoriety. Caltech is the inspiration (and frequent film location) for the California Institute of Science of Numb3rs.
The use of the LA tunnels figured in many films of the 40"s and 50's such as "The Indescribable Man", "He Walked by Night " and "THEM".
At 39:23 whatever Alan is chewing shows how Don got the bad habit of chewing gum with his mouth open.