The character of Millie Carpenter never appears on screen, so an actor was never hired. Millie's off-screen voice is played by an uncredited actor.
The 201 File which Father Mulcahy refers to during the personal effects inventory is an actual record still in use in the U.S. Army to this day. It is an all encompassing record of an Army service member, from start to end of service. It covers promotions, awards, schools, assignments, primary and special qualifications, languages, and other pertinent information relevant to the Soldier's career.
According to the book, "The Short Life and Happy Times of the Shmoo," by Al Capp (2003), "More than fifty years ago, America was taken by storm when Al Capp introduced the Shmoo in his comic strip Li'l Abner. The adorable squash-shaped character was so popular it immediately spawned the largest merchandising craze in the nation's history."
The immensely popular Hula Hoop and Frisbee, which were, in reality, created by toy company Wham-O, were both given a false origin story similar to the one in this episode in the Coen Brothers film "The Hudsucker Proxy" (1994).
In typical Hawkeye fashion Hawkeye, in eulogizing Lt. Carpenter, talks more about himself than the deceased.