When Columbus is fighting the mutineers on the ship they all suddenly stop.The next shot is of the man in the crows nest shouting "Land Ho".Clearly an editing error as March and other actors stop before they hear the signal of land sighted.
In the film, Columbus seems to realize that he never landed in India, whereas in real life, he never realized it. He also talks constantly about having found "new worlds", as if he knew that he had discovered America.
Opening narration perpetuates the myth that people of Columbus' time thought the Earth was flat when in fact they knew it was spherical. Later, when Columbus discusses his plan with Father Perez and another friar, the friars clearly know that the world is round.