When Liz points out the video that suggests Polk incited the riot in 2007, he says "it's not exactly the Zapruder film." The Zapruder film is a film of the Kennedy assassination taken by Abraham Zapruder and believed to be the most complete film of the assassination and therefore the most definitive; because it was withheld from the public in the beginning, it is also held by the proponents of many different theories as proof that something was being hidden or even as proof directly of their favored theory. It is currently held in the Library of Congress and copies are available for viewing in many places online. It has also been the subject of more than one book and a few museum exhibits, most notably in the Texas Book Depository building from which Oswald fired.
Larry spends much of the episode eating and contemplating raspberries, which Charlie questions as a sign of a "new diet" in reference to Larry's preferred diet of all-white foods (which he does break when he feels it's warranted as it's not an absolute diet).