There were two eps when the 4077th gets a visiting surgeon and Potter feels useless in one and sick with mumps in the other. One guest who played a visiting surgeon in one ep was I think Dennis Howard. The guy who played the other visiiting surgeon in the other ep looked like him (if I remember correctly). Weird how similar and similar guested these 2 eps were, huh?

Other lookalike guest were Pat Hingle and Dick O'Neil (who guested many times).

PS Dick O'Neil was in 1965's Gamera alongside future DS actor John Baragrey. Do you suppose O'Neil was very scared when he guested on Mash from his experience years earlier working with Baragrey? Him and Baragrey had no scenes together but they could have been on the same set at the same time anyway.