When Rick and AJ are in the hotel lobby a kid tries to get them to buy a lottery ticket. This is an obvious nod to The Treasure of the Sierra Madre (1948) as well as the offer to invest in a gold mine.
The episode "Emeralds Are Not a Girl's Best Friend" concludes a crossover that begins on the Magnum, P.I. episode "Ki'is Don't Lie", wherein Higgins helps the Simons track the woman with stolen Hawaiian artifacts to Latin America. For repeat and syndication purposes, a second conclusion was also shot, wherein the fleeing villain is caught, allowing the Magnum episode to be wrapped up and the episode to be rerun as a "stand alone" episode. Consequently, the Simon & Simon concluding hour, "Emeralds Are Not a Girl's Best Friend", did not appear in reruns for many years, nor did the original broadcast version of "Ki'Is Don't Lie". Both original versions have since been released on DVD.
As mentioned above, this was originally aired by CBS immediately after its Magnum PI cross-over prequel: this was the very-first S&S episode in what became a "Two-hour Magnum/S&S Thursday-night Prime-time tag-team", Magnum 8PM, Simon & Simon 9PM; this scheduling arrangement lasted a number of years.
The Republic of Costa Nueva is a fictional country.