Although "Goodbye, Farewell and Amen" was the final episode that aired, the episode "As Time Goes By", which was the second last episode that aired, was in fact the final episode filmed. Because the ranch set had been destroyed by a brush fire, "As Time Goes By" was filmed completely on the indoor sound stage set.
When Charles jumps on the grenade Rizzo tells him that he threw himself on it "faster that Snyders Hounds." Frans Snyders was a Flemish painter who did a series of paintings portraying hounds bringing down wild game. The phrase "faster than Snyders hounds" became an adage in the South and Appalachia meaning great speed.
This was the first appearance of Soon-Lee (played by Rosalind Chao). Not only would she marry Klinger in the series finale, but she would become a regular on the short lived follow up After MASH (1983).
During the time-capsule burial scene, Hawkeye and BJ mention the names of Radar and Henry Blake. However, there was no mention of Trapper John. Major Frank Burns was mentioned in the very last scene of the episode, as Hawkeye, BJ and Charles discuss possible additions to commemorate him.
In this, the final standard episode of the series, the MASH personnel bury a time capsule to be unearthed in 100 years. In the first episode, the words "Korea - A Hundred Years Ago" appeared on screen before the opening credits.
The episode's title comes from the song "As Time Goes By," made most famous as the song from Casablanca (1942). The song itself predates that film by 11 years, however, and has been used in many movies and televisions shows.