Wayne Rogers and Mike Farrell are the only two actors from M*A*S*H(1972)who were the predecessor and replacement to each other's characters to appear in this special and this is the first and only time the two actors ever appear onscreen with each other. McLean Stevenson,who played Harry Morgan's predecessor Lt. Col. Henry Blake,died six years earlier and Larry Linville,who played David Ogden Stiers' preceding character Frank Burns,died two years before this special was made(Stevenson and Morgan did act together in the M*A*S*H(1972) season 3 premiere episode "The General Flipped At Dawn" when Morgan appeared as the lunatic General Bartford Steele a year prior to Stevenson's departure from the series and Morgan joining as Col. Sherman Potter). This was also the only time that Wayne Rogers and David Ogden Stiers had appeared onscreen together as Wayne had left the series two years before David joined the show. It was not Rogers' first onscreen appearance with Harry Morgan though as,even though he left the series right before Harry Morgan joined as a regular,the two did share a scene in the aforementioned M*A*S*H(1972) episode "The General Flipped At Dawn". In all,McLean Stevenson and Mike Farrell were never onscreen together for anything(Farrell joined the show following Stevenson's departure),nor did Stevenson and David Ogden Stiers ever appear onscreen together as Stevenson had left the series two years before Stiers joined the show and had died several years before this special was made. Larry Linville and David Ogden Stiers never made any onscreen appearances with each other as Linville had already left the show when Stiers joined it and Linville passed away two years before this reunion. Besides this reunion special and the documentary special on the series "Memories of M*A*S*H"(1991) that aired on CBS in November of 1991 plus several other bios and documentaries on the series with cast interviews and clips from the show,the only other showing of the entire M*A*S*H(1972) franchise to include every single one of the cast and characters from the series was the M*A*S*H(1972) season 7 episode "Our Finest Hour" in which Wayne Rogers,McLean Stevenson,and Larry Linville,who had all left the series long before this episode had aired,appear as their respective characters in flashback clips from the show's previous seasons.
Although the original series aired on CBS, as did the 20th anniversary special, this special aired on Fox, a network founded by and named after the show's production company, 20th Century Fox. In the decade that passed between the 20th and 30th anniversary specials, Fox had taken over the rights to the National Football Conference of the National Football League from CBS, and in the process, switched a number of CBS affiliates, many of them in NFC markets, to Fox, which later purchased these stations in 1997. Thus, several stations had the privilege of airing both of these specials: KSAZ in Phoenix, WTVT in Tampa Bay, WAGA in Atlanta, WJBK in Detroit, WJW in Cleveland, KTBC in Austin, KDFW in Dallas-Fort Worth, and WITI in Milwaukee.
Though this is the only time Wayne Rogers and his replacement, Mike Farrell, appear on screen together, they don't even shake hands or interact.