Hawkeye mentions to Frank about getting his credit card number. While credit had been around for years, actual credit cards didn't arrive until after the Korean War ended.
In the end credits, actress Louisa Moritz, who played Nurse Sanchez, is credited as Louisa Mortiz.
When Trapper and Margaret are trapped in the supply tent, the "wire mesh" on the window wobbles revealing that it is actually made of rubber and not wire.
The Intelligence Officer Radar is speaking to refers to an "intelligence map' hanging on his wall. This is a standard atlas map of the Korean Peninsula. It is highly unlikely that a map with highly sensitive information such as troop movements and enemy locations would be posted in view of the public.
When the announcement about the bug-out is heard, Trapper and Hawkeye are leaving the supply tent. Trapper says, "Evacuate to where?" As bombs go off, Trapper is clearly saying something that can't be heard, and then Hawkeye says, "Now the Book of the Month club will never find me." It appears that the filmmakers decided to cut one line.
Margaret asks Trapper for help getting into the supply room because they desperately need supplies. After they are trapped in the supply room, no one tries to look for them (with Henry hurt, that leaves only Hawkeye and Burns to operate) or try to get the supplies they so desperately needed until the next morning.
Henry and Fr. Mulcahy were using the latrine when it was shelled. However, when they were pulled out, they were still fully dressed.
Hawkeye throws the live grenade out the OR window without checking to make sure no one is out there.