At the beginning of the story, Straker flies to Sao Paulo, Brazil for an overdue inspection of the SHADO setup there, followed by Foster. São Paulo is a state in the South American country of Brazil. Foster had an earlier adventure in Brazil in "The Alien Totem".

On page 1, Straker remarks to Lt. Gomez that UFO landings are not being properly intercepted in the region.

When Straker is attacked by a tribesman with a blowgun, Lt. Gomez exclaims, "Santa Maria!" This is a Spanish phrase referring to the Blessed Virgin Mary.

On page 2, panel 3, the headline of the newspaper being read by Foster can just be made out as "Movie Tycoon Assassinated", with a photo of Straker beside it.

Major Enchada tells Foster the Indian who shot Straker with the poison dart was a Curura. As far as I've been able to determine, this is a fictional tribe.

In this story, a SHADO mobile is depicted as able to travel on water. This capacity was mentioned in the "SHADO Defence: SHADO Mobiles" article in the 1970 UFO ANNUAL published by Polystyle Publications (the same publisher as Countdown/TV Action). This capability is also demonstrated in "Recordbreakers". We also see here that the mobiles have an access hatch on the rooftop of the cab.

The actual name of the Brazilian river in this story is not specified. Enchada's reference to it as the Rio del Muerte (River of Death) is likely just a euphemism for it. There is no river with that name officially.

Foster is forced to wrestle what Enchada describes as an alligator, when it menaces an Indian boy. But there are no alligators in South America! It must be a crocodile.

The end of the story depicts Straker using the mobile's roof-top gun to kill two of the three aliens holding the village hostage and destroying all three landed UFOs present.