Revealing mistake: When Hawkeye and BJ are in the showers and Margaret steals their towels and clothes, the duo head back to the Swamp naked, but we can see the top of whatever Hawkeye's wearing.
Continuity mistake: Charles arranges a prank that involves a cake. The cake looks totally different in the respective shots. At least three cakes were involved: The one Klinger gives to Margret looks different from the one she holds in her hands when walking over to Capt. Hill. The one she holds in her hand in the closeup counter shots is yet another pie.
Answer: It is actually Cencompac for Central Command of the Pacific. It is like the headquarters for all military activity in the Pacific Region (Japan, Korea, Okinawa, etc. The newer version of that is United States Pacific Command (USPACOM).
EMTurbo
And the abbreviations were used mainly by the Navy. Especially CENCOMPAC.
Https://en.wikipedia.org/wiki/United_States_Indo-Pacific_Command.