Veteran character actor Dick Wilson aka Mr. Whipple can be seen as a cocktail server at the party at the end.
First of 2 Emmy awards for the series was from this episode. Primetime Emmy [Winner] (1967) Outstanding Directorial Achievement in Comedy-For episode "Royal Flush" for James Frawley.
First aired episode of The Monkees.
The gold and 309 / Usurper thrones appear in The Prince and the Paupers (1967) and other episodes of the series.
The first of many episodes "The Monkees" that utilized the beach set at the (then) Columbia Ranch in Burbank. It can be seen in several Screen Gems productions made around the same time.