You are correct! Many items on the show are out of date - just a couple examples:
A chocolate (Hershey,s) bar given to a native has the Hersheys logo turned down but the bar code is plainly visible! In the club, a much more modern red helo is pictured on the wall (a "Huey"?), and many other date related mistakes are easy to notice on all the episodes.
Guess the production crew didn't realize how popular the series would be so didn't bother with such obvious mistakes.
You, sir have now given me a whole new reason to watch MASH re-runs! Only I'll have the sound off so as not to distract from looking for mistakes.
It occurred to me that some of the equipment pictured in these posts from the show may not even be communications equipment, but instead old test equipment.