While discussing a patient's irregular heartbeat, Hawkeye refers to it as "arrhythmia" while Potter uses the term "dysrhythmia." This is not a terminology error or anachronism, nor is Potter being cute by using some sort of unique folksy cowboy-dialect self-invented word, as he is occasionally wont to do. Cardiac dysrhythmia and cardiac arrhythmia refer to the same thing; both are synonyms for an irregular heartbeat and can be used interchangeably.
Second and final series appearance of Richard Lineback. He previously appeared in Season 8's "Dear Uncle Abdul" as Eddie, a somewhat "slow" but extremely loyal soldier who's protective platoon leader gets sent home.
When George Wendt appeared in this episode, the series' final season, he was also starring on Cheers which was in its first season on NBC.
As Hawkeye and B.J. have clearly made their costumes from scratch, they evidently used items found around the camp to do so. The most obvious is B.J's clown shoes, which are made of hot water bottles.
While preparing to treat Pvt. La Roche (George Wendt) for having a pool ball lodged in his mouth, Winchester calls him "Private Mosconi". This is not an error, but a joke referencing world famous pool player Willie Mosconi, aka "Mr. Pocket Billiards," who, between 1941 and 1957, won the World Straight Pool Championship an unmatched fifteen times, and through his fame helped to popularize pool as a national recreational activity.