After clearing the centre-most portion, I rashly charged ahead on my horse and noticed a speck in the sky. Looking up, I saw it was a cow! I then proceeded to shoot the cow, and watched as it plummeted to the ground.
As you can see, I took two pictures of said cow, though there were more. Another was floating above the right-most portion, and another was just to the right of the one seen in my images.
I searched for more cows, and saw another minding its own business along the top of the ridge. Racing up to it, it charged headlong off the edge and, in a scene straight out of Looney Tunes, ran across the nothingness and stopped, floating, above the canyon.
Now I wonder if anyone else has experienced this glitch? One of my mates, Rambo, claimed to have seen one floating above the barn at MacFarlane's Ranch as well.
If you have seen this, please say so in the comments!