The medical officer who comes to treat Colonel Klink is named "Dr. Kronk". The name is something of an inside joke: "Kronk" is the phonetic spelling of the German word for "sick".
The sequence where Hogan, LeBeau, and Newkirk go out to retrieve the penicillin - from exiting the tunnel to actually opening the dropped box, is re-used from Nights in Shining Armor (1967); LeBeau: "If they find it, they find us".
The 4 dogs that Major Hochstetter uses for tracking are beagle-type hunting dogs, of the kind that are used to track foxes during hunts.
This is the first guest appearance of Brenda Benet in the series. She plays an Underground agent named Jeanine Robinet. She also plays Jeanine Robinet in The Antique (1969).