The "Rock The Vote" event shown at Cambridge, MA is aimed at encouraging young people to vote in the US general election. The band playing at the event, Barenaked Ladies, are all born and raised in Canada.
The opening line of President Bartlet's speech, "Joy cometh in the morning...", is from Psalms 30: 5: "For his anger endureth but a moment; in his favour is life: weeping may endure for a night, but joy cometh in the morning."
When President Bartlet (Martin Sheen) is giving his speech in East Lansing, the Flag of Mississippi is clearly visibile on the stage. East Lansing is in the State of Michigan, and the Flag of Michigan is not visible anywhere during the scene.
Kennison State University is fictional. In the previous episode, 20 Hours in America: Part II (2002), there are several similarities between Kennison State and the University of Iowa. This episode confirms that Kennison State is in Iowa. FBI Agent Casper also states that they have found suspects in Johnson County, IA, the same county where the University of Iowa is located.