The first feature film to combine stop-motion animation with anamorphic CinemaScope and color.
A Spanish-language version was shot simultaneously with the English-language version.
The beast was animated using two separate stop-motion animation methods. A two-foot-high armatured, rubber-covered model was moved, exposing a frame at a time. Also utilized was replacement animation, a technique that involved several different models of the same character made of plaster, each slightly different to represent a particular action. When filmed in sequence for a few frames per second, the illusion of motion is achieved. The breathing effect of the creature was accomplished by pumping air in small increments into a cavity of the throat of the two-foot-high model and then releasing it in the same manner. When seen on the screen the throat rises and falls creating the breathing effect. Two large rubber feet were filmed for the shots of the monster walking, which were worn as shoes by a technician.
The costumes worn at the village festival about half-way through the movie are typical of Chinelos, a costume that was developed primarily in the Mexican state of Morelo by descendants of the Aztecs to mock European invaders and their ways. The costume consists of a tunic, a mask, a large plumed hat, and gloves. The masks have European features and an upturned beard, again to help in the mockery. Typically, these costumes would appear at festivals such as Carnival where mocking the establishment is encouraged or allowed.
The beast is barely mentioned throughout the film and, except for a shadow at 0:44, isn't seen until 0:59 in the film.