Ron Silver, who played Bruno Gianelli, was a long-time Democrat. He switched sides and actually spoke at the 2004 RNC, mimicking his character (Bruno Gianelli), who switched sides from working with the Democratic Bartlett White House to working with the Presidential Republican Arnold Vinick Campaign.
At about the same time as this episode aired, a real-life news story developed that closely followed the plot. In the show, a religious conservative claims to have private assurances from Vinick that future Supreme Court appointments would be "anti-abortion". In real life, a conservative leader claimed that he had similar inside information about the President's most recent nominee for the Supreme Court. It's common for West Wing to develop plots loosely based on news stories, but unusual for a news story to develop at about the same time as a similar plot thread from the show.
Arnold Vinick states that he is not a veteran of a foreign war. Alan Alda, who actually did serve in the military, including a tour in Korea, is best known for playing Captain Hawkeye Pierce on the show M*A*S*H.