It is established in other installments that Klinger's blood type is B+ and Charles's is AB-. In this one, they have the same blood type.
Hawkeye says he has had claustrophobia since he was a child but he hid in a trunk in "M*A*S*H-The Pilot" and squeezed into a jeep in "Dear Peggy."
When Klinger is asked if there is room under the desk to hide Klinger states that there isn't due to his full skirt. When Klinger gets out and then dives back under the desk he is wearing a robe and men's pjs.
When the convoy sets off its night time during the journey there's blue sky in the background then it's night when they reach the caves.
When Hawkeye and Margaret are operating, Hawkeye puts a clamp in the lamp. In the next shot, it is gone. In the next following shot, it returns.
When Hawkeye and Margaret are performing surgery on a patient, Hawkeye comments that with Klinger and Father Mulcahy's blood in him, he'll wake up singing "Ave Maria" in Lebanese. Since Father Mulcahy contracted Hepatitis from a soldier previously, he should not be donating blood for any reason.
Capt. Hunnicut struggles with how to transport a patient whose leg is in Buck's traction. In a medical unit that is mobile and had such a high rate of patient turnover it's highly unlikely that said unit would not have traction splints available.
When talking to the fire control center, Colonel Potter is asked to prove his identity by authenticating "Victor Zulu". During the Korean War the US military still used "Zebra" to represent the letter "Z". In the modern spoken alphabet, where "Z" is represented by "Zulu", that letter is reserved for Universal Time Coordinates (previously known as Greenwich Mean Time), and never used in code challenges.
When Hawkeye and Margaret hug each other after a shell explodes close by, Loretta Swit's fingernails can be seen to be over 1/2 inch long. No nurse, especially a head nurse, would have fingernails that long.
This episode and multiple others use a bus for transportation. The War ended in July of 1953. The bus they are using is a 54 Ford which wouldn't have been sold until Sept of 1953. The year of the bus is obvious because the grill is what is known as the walrus. Very different from the other years that share the same fenders and hood 53-56.