Continuity mistake: At the start of the ball game Tzekel-Kan puts the ball down on a flat surface, shouting "Play ball.' But in the next shot there are a couple of tiny pieces of rock near the ball.
Continuity mistake: When Miguel and Tulio first arrive at the El Dorado island, the moss and plants near Whistling Rock (shaped as an eagle's head) change between shots and also change later in the film.
Continuity mistake: The shape of the spear that Tzekel-Kan's assistant has, changes in the scene where he first sees Miguel and Tulio next to the waterfall.
Continuity mistake: After Tzekel-Kan pushes his assistant into the potion, the bowls and items that were there previously have vanished.
Continuity mistake: When Miguel kisses the skull after arriving at El Dorado's island it is facing towards the ocean. But when Cortes arrives later on, it is facing away from the ocean.
Continuity mistake: When Miguel and Tulio are sailing out of El Dorado and almost hit a stalactite, between shots the stalactite becomes more pointy.
Continuity mistake: When Miguel and Tulio first arrive at El Dorado, the volcano is visible near the palace, but it disappears later in the film.
Continuity mistake: Altive kicks Tzekel-Kan's jaguar-like monster in the eye, leaving several cracks, The cracks constantly change between shots, particularly in the scene where the monster has cornered Miguel and Tulio at the edge of the cliff over the water.
Continuity mistake: When the two men are under the deck planning an escape, Tulio has a black eye. A little later, when they are escaping by boat, the black eye is gone. A black eye would have taken longer to heal.
Continuity mistake: The skull that Miguel and Tulio meet at the beginning, is very obviously different to the one Cortes crushes later on.
Continuity mistake: When Miguel is feeding the birds, they switch position between shots.
Continuity mistake: During the scene when Miguel and Tulio are having an argument, Tzekel-Kan, who is listening to them, changes position between shots.
Answer: Miguel had just told Chief Tanni how loyal Tulio and he were to each other. Then he overheard Tulio saying to Chel that he wanted to go to Spain with her, ONLY with her "Forget Miguel." That's why Miguel was so upset, because Tulio excluded him from his plans and his life.