Edward Winter first appeared as Capt. Halloran in "Deal Me Out" (8 December 1973), but would later play the paranoid Col. Sam Flagg six times in the series. ("Halloran" may have been one of Flagg's many aliases; when he and Sidney Freedman meet in a later episode, Flagg reminds Freedman they'd once played poker together.)
Sidney mentions a soldier who, to get out of the Army, insisted he was a cockroach, to which Hawkeye quips that his name must've been Pvt. Kafka. Franz Kafka is an author famous for "The Metamorphosis," a 1915 novella about a man who wakes one day to discover he's inexplicably been transformed into a giant cockroach.
Loretta Swit does not appear in this episode. Coincidentally, she also does not appear in later episode "The Chosen People (1974)", the only other episode guest starring Pat Morita.
CID means Criminal Investigation Department. A CID officer is exclusively involved in the investigation of crime(s) assigned to his department.