Goofs

The shadows on Prairie Dog change depending upon whether it is a long shot (He is in full sun.) or close shot (His face is in part shadow.).

The night before they enter the canyon of gold, Colorado is threatening Mackenna with a knife. The position of the knife changes back and forth from the tip of the knife on Mackenna's chin and on his throat.

When Colorado holds onto Mackenna's hair, in some shots there is hair falling over Mackenna's forehead, and in others there is not.

The huge shadow of the rock pinnacle abruptly vanishes for no apparent reason.

The cloud formation changes while jumping the earthquake chasm.

In a key scene, a lengthening shadow at sunrise points to the destination location. As the sun rises, shadows get shorter, not longer.

Gold is not shiny in its natural state. It is a dull grey yellow. This is a common error in movies and stories.

The movie begins with a song about a "Turkey Buzzard" during a montage of "vultures" flying over the desert; none of the birds are turkey vultures. Some of the birds are not even vultures. Despite common use in popular culture, members of the vulture family are not buzzards. Hawks are buzzards, members of the Buteo genus. Buteo is the Latin name of the common buzzard.

While crossing the desert, Inga faints and falls off of her horse. Mackenna goes to her assistance, while Colorado wants to shoot her. Mackenna and Colorado argue over killing her, and echoes of this argument are heard. But the mountains are miles away and there is nothing else for the sounds of their voices to bounce off and create those echoes.

Following the escape from the soldiers' ambush when Colorado, Hachita, and Hesh-Ke catch up with MacKenna and Inga, a conversation ensues in the desert and all the voices have echoes yet they are in a very wide open space.

When Colorado and the gold seekers break out of the box canyon, it is night. Despite that, the breakout takes place under a bright blue nighttime sky. Obviously the scene was filmed during the day, using a filter to darken the images, which was not dark enough to mask the blue of the daytime sky. Incorrectly regarded as a goof. This is a common practice in old movie-making called "Day For Night". If filmed realistically at night, you wouldn't see anything on the screen because night is dark. So it's filmed in the daytime in the proper light, then post-processed with a dark blue filter to "signify" nighttime (at least in Hollywood).

During the chase toward the river, camera-vehicle tire tracks are visible in a shot of the Indians.

In opening scene, with the overhead shot of the old Indian from a helicopter, horseshoe prints can be seen going around in circles, where they were obviously taking various shots for the movie, and synchronizing with the camera.

During the climax, numerous effects shots appear to be stretched out, the result of having been filmed in spherical 35mm (i.e., "flat") and then projected through an anamorphic lens.

The birds are Griffon Vultures (not Turkey Vultures); also seen circling in one of the scenes appears to be one of the European species of Kites - either a Red or Black Kite (difficult to tell which one due to the poor lighting).

The shadow is the key to the location of the canyon, but it will point to that precise spot only a few days each year.

Additional Apaches enter the canyon to hunt down the gold seekers. However the Apaches - along with everyone else - do not actually know the location of the canyon, and the shadow of the rock that indicates it will have faded at least an hour before. In fact, how did they even know that anyone had gone into the canyon, so why would they go after them?