Corrected entry: The main background villain in the story is Hernando Cortez, but he didn't come to South America to seek El Dorado. He subdued the Aztec empire in today's Mexico between 1519 and 1521. The only Spanish expedition to seek out El Dorado at that time was under the command of Gonzalo Pizarro.
Corrected entry: Throughout the film, the characters keep using the phrase "to err is human, to forgive . . ." (not usually finishing it). The thing is that the movie is set somewhere around the year 1500 (right after the introduction song, they show you the year when the story is supposed to take place) and that phrase was "made famous" by Alexander Pope, an English poet born in 1688.
Corrected entry: The movie is set in 1495, and the main enemy is the historical leader Hernan Cortez. Cortez was born in about 1485; he should be about ten years old.
Corrected entry: After yellow-hair has eavesdropped on black hair, he sadly walks down the steps. Altivo (the horse) walks down after him. HORSES CAN'T WALK DOWN STAIRS.