During the opening credits, Esteban is seen controlling the golden condor using 2 control levers. However, during the episodes proper, he only uses one (the condor just has one, shaped like a cobra).
Despite the characters continuously interacting with new cultures that previously had little or no contact with each other, there is never a spoken language barrier to overcome. All characters, whether Spanish, Incan, Olmec, or Hiva, speak the same language perfectly with no explanation for this phenomenon.