According to the legend of El Cid, in his youth Rodrigo came across a leper sinking in quicksand crying for help, but none of the bystanders dared touch him. Rodrigo pulled him from the bog, clothed him in his cloak, housed him in a barn, and went to get him some food. When he returned, he found the leper had transformed into an angelic figure that identified himself as St. Lazarus. He said "For your bravery and kindness, you will enjoy success as a warrior. You will win battles upon battles and never know defeat." In a nice nod to the legend, this movie contains a scene wherein the banished Rodrigo encounters a thirsty leper who begs a drink. After unhesitatingly offering his own pouch, the Leper thanks him by name. "Who are you?" asks Rodrigo. "I am called Lazarus", the leper answers. Then he crosses Rodrigo with his staff. "May helping hands be extended to you everywhere you go, my Cid."
El Cid and his wife Jimena Díaz lived peacefully in Valencia for five years until the Almoravids besieged the city. According to legend, El Cid was fighting one of the men when he was shot in the heart with an arrow. Valencia's troops were losing spirit when Jimena thought if she set the corpse of El Cid atop his horse Babieca, the morale of Valencia's troops would soar. Alfonso ordered the city burned to prevent it from falling into the hands of the Almoravids. Valencia was captured by Masdali on May 5, 1102 and it did not become a Christian city again for over one hundred twenty-five years. Jimena fled to Burgos with her husband's body. Originally buried in Castile in the monastery of San Pedro de Cardeña, his body now lies at the center of the Burgos Cathedral.
According to Time Magazine, this movie required seven thousand extras, ten thousand costumes, thirty-five ships, fifty outsize engines of medieval war, and four of the noblest old castles in Spain: Ampudia, Belmonte, Peñíscola, and Torrelobatón.
Charlton Heston and Sophia Loren reportedly got off on the wrong foot early in filming which set a bad tone for their working relationship for the rest of the shoot. Heston later said he regretted the way he behaved towards Loren during filming, feeling in retrospect that he'd been unprofessional and unfair to her and wished he'd been kinder and less stubborn towards her.