We see that Don still has an issue or pain with his right hand which in the previous episode Friendly Fire (2009) was seen to shake in the aftermath of having to shoot his mentor.
Sam Lloyd, the UFO group leader, plays a very similar character in The West Wing's The Crackpots and These Women (1999).
At 36:02 Colby says "You can walk all the way to Bullhead Arizona". Despite the unlikely name, Bullhead truly is a city in Arizona.