An actual farewell party for Radar when he left, rather than it being interrupted by wounded arriving, but then that's the art of war sadly.
In "The Price" I would have not had the old Korean colonel die and I would not have had the kid that Hawk & BJ tried to protect run away.
In "Margaret's Marriage" I would have had the episode end where Frank stands alone and sadly says "Goodbye, Margaret." The scene afterward with Hawk, BJ & Potter in the Swamp trying to console Frank I felt was kind of a forced, shoe-horned scene.
Trapper and his wife would have adopted Kim instead of having his mother show up. I felt that was one of Trapper's best episodes.
Could post so many more but don't want to be piggish :)