William Christopher contracted an almost fatal case of hepatitis at the start of the fifth season, resulting in his having to miss several episodes. As a result, producers were planning to write Father Mulcahy out of the show. However, Alan Alda pushed to keep him on the series, knowing how dependent Christopher was on needing steady work to help raise his autistic son. Alda went as far as writing an episode to incorporate Christopher's real-life illness into Mulcahy, helping to convince producers to keep him on the show.
Radar's teddy bear, once housed at the Smithsonian, was sold at auction July 29, 2005, for $11,800. (It was originally found on the Fox Ranch, where the series was filmed, and became part of the show.)
Klinger often mentions a restaurant in his hometown of Toledo, Ohio called Tony Packo's, specializing in Hungarian Hot Dogs. This is a real restaurant on Toledo's east side that is still popular with many who live in Toledo and the surrounding area.
Jamie Farr and Alan Alda were the only two main cast members to have actually served in the U.S. Army in South Korea. Both of them did their tours of duty after the 1953 cease fire. Farr was drafted, serving in Japan at Camp Drake before eventually touring and performing throughout South Korea with friend Red Skelton. Alda voluntarily enlisted the Army Reserve after graduating from Fordham, and completed the minimum six-month tour of duty as a gunnery officer.
The death of Lieutenant Colonel Blake was largely controversial and polarizing amongst television viewers and critics. While it was known that McLean Stevenson was permanently leaving the series, no one expected to see him killed off in such manner, and such a move was largely unprecedented for a primetime television series at the time. Writers and producers defended the move, which was largely viewed as a statement on the horrors of war.