When 'The Cowboy' chopper pilot wants to go home in an early episode and is taking Col. Blake to Soeul in the back ground as the chopper is heading back to the 4077 on the hillside you will see a couple of telephone poles. You have to look fast as they aren't on the screen for long.
Did any of you stop to wonder what Radar and later Klinger was calling people on? If that was a phone was it a cell phone? I believe it worked like a radio myself but I could be wrong and they used telephone lines
My father served in Korea and he was one of the many to "string" telegraph/telephone lines through out the country. So, in my opinion, this is not a slip-up.
Considering the fact that MASH was filmed in the 1970's at Fox Ranch in the Santa Monica Mountains area of California, I doubt what we are seeing are telegraph poles