The building which appears as the East European Consulate is the Philippine Consulate on Pali Highway in Honolulu.
Morton Stevens intended this to be his last Five-O musical score after nine-plus years (he had done the filmed-earlier "Up the Rebels" and "Angel in Blue," which was shown much later in the season, before this one). Stevens did sit out the rest of the 1977-78 season and all of 1978-79 before returning to Five-O for the final year.
Guest starts Kurt Russell and Tim Matheson co-starred in the television western The Quest (1976) prior to appearing in this episode.
Kurt Russell, who plays Peter Valchek, and Charles Hallahan, who plays TV reporter Larry Kent, appear as colleagues in The Thing (1982).