During the climactic gunfight Phelps and Cardoza are atop a hill with the agents at the bottom. Throughout the battle, Phelps and Cardoza fire upwards and yet we still see the bullets strike around the agents.
Jack Cole insist that Jim Phelps kill Colonel Cardoza. After Phelps pretends to shoot Cardozo, Cole checks to verify that Cardozo is dead. Cole touches Cardozo's body, and accepts that he is dead, but he should have realized it was a ruse because he would have felt his pulse or heartbeat.
37:51 When Cole gets off his horse and walks down the trail he is not carrying anything. When he falls, he ends up laying on a pile with a gun, canteen and saddle bag.
During the supposed shooting of Colonel Cardoza, the bright blue back wall of the set is visible. When the shot changes back to the location shot, there is nothing but dirt and rock behind the stones.
When Cole shoots the guards, no blood or bullet holes are seen on their bodies.
At the front of the prison the sign says in Spanish "PRISIION PROVINCIAL". It should read "PRISION PROVINCIAL".
At the front of the prison the sign says in French "SEULEMENT LES PERSONNES AUTORISEES". It should be written in Spanish.
When the police catch up to the men in the cave and Phelps shoots at them he is above them on the hill. when he takes his first shot the rifle is pointed upwards but there is a ricochet downhill by the police.
33:48 When Jim is getting the burro he leaves the packs that were on it. He should have emptied the sacks and saved them to put treasure in them .
A soldier says in bad Spanish "Otro caballo por él" (i.e. "Another horse for him"). He should say "Otro caballo para él".