One thing that I always found interesting in this episode as Hawkeye's
final (phone) conversation with Frank. He says something along the
lines of "we fell the same way Frank - it was a pleasure to have known
you."
As Hawkeye hated Frank, you'd think he would have at least given Frank
the "raspberry" or told him off one last time (though the "it's a
pleasure to have known you" line could be taken as insincerity).
The only reasoning I can think of is that they still wanted to send of
Larry Linville in a comical "Frank went bananas" way, rather than the
inept doctor/major who was a thorn in the others' side. And since
Frank was off camera, it would seem heavy handed of Hawkeye to tell him
off over the phone.