John Spencer (Leo McGarry) died of a heart attack on December 16, 2005, about a year after his character experienced a nearly fatal heart attack on the show. Martin Sheen gave a brief memorial message before "Running Mates (2006)", the first new episode that aired after Spencer's death. The loss of John Spencer's character was addressed beginning with the episode "Election Day: Part 1 (2006)", which aired on April 2, 2006.
Despite the fact that Josh (Bradley Whitford) was shot and had extensive open-heart surgery in the second season, when Josh and Donna (Janel Moloney) are in bed there is no scarring on his chest. Likewise, Donna has no scars from the bombing of the CODEL in the end of the fifth/start of the sixth season.
Josh talks about people going to the polls in Oregon but the entire state votes by mail.
At one point, Bob (Stephen Root) says to Bruno (Ron Silver) that North Dakota has gone Republican for the last 40 years (approximately 1966), yet Bartlet (Martin Sheen) won both of the Dakotas four years prior.
When Josh (Bradley Whitford) goes out to get fresh air, it is completely dark, even though it shouldn't be.