The series regularly bounces back and forth in time, none more evident than in this episode. It takes place between the New Year's Eves of 1950 and 1951. In "Welcome to Korea" (1975), Col. Potter arrives to take command on Sept. 19, 1952. There are also several Christmas episodes, and other annual events that take place over the shows 11-year run, despite the actual war upon which it's based lasting only 3.
The second episode in which one of the surgeons has a scheme to make money by betting on major league baseball games. In Out of Sight, Out of Mind (1976), Frank Burns listened to the live radio broadcast of games, then when the games were rebroadcast the next day he would bet other 4077th members as to the games' outcome.
So, in this episode they are apparently listening live to the "Giants win the pennant" game. With the game ending roughly around 4-5p in NY, it would be 5am or so in Korea rather than the middle of the day as the episode appears to show.
BJ mentions "that new kid Mays," referring to the great Willie Mays who was called up to the NY Giants in 1951. Even though the Giants would not move to San Francisco until 1958, it was clever to have BJ mention him as BJ is from the SF area.
If this timeline is to be considered the accurate one, it means that, as of the end of the war in "Goodbye, Farewell, and Amen" (1983), Hawkeye, Klinger, Margaret, and Father Mulcahy - the only characters present throughout all 11 seasons of the show's run - have been serving in Korea for almost 3 full years, longer than any tour of duty would last.