Dr. Matthewson's line, "fellow sons of bitches," is a reference to original Manhattan Project scientist Kenneth Bainbridge. Following the first successful test explosion of an atomic bomb on July 16, 1945, Bainbridge said to fellow project scientist J. Robert Oppenheimer, "Now we are all sons of bitches."
The science projects and kids in the background of the science fair scenes were actual NYC middle school students with real science projects which were submitted to the NYC borough-wide science fair. These scenes were filmed over a three day period at the Penta Hotel in NYC on 33rd St.
Early in the film Paul sees his mom is reading a book which she describes as just another novel. Later in the film when the helicopter arrives over the house, the camera shows the book is by Frederick Forsyth, and the title is "the fourth protocol", a fiction book which involves a compact nuclear weapon, which was also made into a film released in 1987.