Hangman

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.

While trying to figure out how to stop a shooter, Charlie asks the agents if they "remember when we used covering sets". While it might make sense for him to expect Don and David to remember, it makes no sense for him to expect that of Colby, given that the case in question was from Episode 4.01 "Trust Metric", in which Colby was not a member of the team but the target of the search.

[This appears on the beginning of the episode] 4 letters 400,000,000,000 stars 718 meters per second 60 stitches