Laughing tracks
Laughing tracks are played in the background of the show, to obviously emulate laughter, as M*A*S*H was not filmed in front of a live audience. However Gelbert and the executive producer, Gene Reynolds, did not want a laughing track whatsoever but CBS overruled their decision. Although you can notice that the laughing tracks dies down with each passing season.
Real soldiers
Both actors Jamie Farr and Alan Alda served in the U.S. Army. Alda served in Korea in the Army Reserve for six months while Farr was sent to Japan. That’s pretty noble of the two famous actors.