Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
A man, his daughter, and his granddaughter and his two Indian friends are chasing some US Army deserters who have kidnapped young women to sell as slaves in Mexico. They stop at an abandoned adobe structure somewhere in New Mexico. The little girl sees a tortoise, picks it up, then sets it down. That's it. It's just a tortoise cameo. There are no tortoises native to New Mexico where this was filmed, so it's an import. The film shows other animals, owls, raptors, and snakes, that are used either in Indian witchcraft or are shown as part of the Native American view of the world where animals are guides of some kind, so maybe the tortoise was meant in the same light. We never get an explanation for it.