Reddit reviews TV's M*A*S*H: The Ultimate Guide Book

The production code is listed in the last frame of the credits of each episode--see a column of them here. In the context of MASH, I know it is a pretty strong indication of what order episodes were written in, although they weren't always broadcast in the same order or even intended to be. For instance, when Netflix uploaded S6-11 of the series, they originally listed them in production order--this led to a continuity error where Period of Adjustment (when Klinger has trouble being the full-time Company Clerk) was listed before Radar even went home in Goodbye Radar.

Now, I'm not 100% sure what the production code is intended for, although there's a pretty strong correlation between the letter and the season...so my guess is that those "1-G" episodes were all written as a batch, between seasons, and intended for Season 10, but some of them got carried over.

EDIT: Sorry, just realized I didn't really answer your question. I'm sure I noticed the original discrepancies years ago, when my dad printed off an entire episode guide for me. Pretty sure it was this text, though it might have been a different URL in those days. If you want to know more MASH history, I recommend this book and refer you to these websites:

http://www.mash4077tv.com/2015/04/seasons-6-11-added-to-netflix-but-not-gfa/
http://bestcareanywhere.net/