Aaron Sorkin found Allison Janney lip syncing to Ronny Jordan's The Jackal in her trailer, and wrote it into the episode. Janey was initially doing it too well, and was told to make it more awkward.
Referenced in this episode, General Sherman's "Special Order Number 15" was issued on January 16th, 1865, providing 40-acre parcels of land and mules to freed slaves. However, President Andrew Johnson effectively revoked the orders four months later, not four years later as the episode mentions, with the "Amnesty Proclamation" on May 29, 1865.
This is the episode where C. J. Cregg lip-syncs to "The Jackal", a song from the Ronny Jordan album, The Quiet Revolution.
In the opening scene, the front of the White House is shown and the flag is at half-staff.