When Trapper stops the Jeep because he has to go, it's the same spot where Father Mulcahy gives a wounded soldier a tracheotomy in Mulcahy's War (1976).
The character played by Robert Alda has the same surname as Giovanni Alfonso Borelli, a 17th-century Italian physiologist who carried out landmark research in blood constituents and biomechanics. His birth-date was January 28, which is also the birth-date of Alan Alda.
Hawkeye says " I'm a gynecologist for the FBI." A popular radio show of the era starred Dana Andrews in " I was a communist for the FBI".
Dr. Borelli (Robert Alda) says he had enough of the front lines in WWI and WWII. Alda was 60 when this episode aired. At that age during the Korean War, Borelli would have been in his early 20s at the time of WWI.