After visiting T'Hacka's village, the children decide it is too dangerous to proceed south, as a Spanish fort protects a mountain pass. The children then return to a northern coastal fort already encountered, yet a subsequent battle scene shows explosions going off over the mountain fort which was only discussed by the children but never actually visited.
When the characters are walking through the desert, they pass several saguaro cacti. Saguaros are not native to South America.