During the opening sequence, the cloud formation behind the eagle looks like a herd of horses. Also, when Spirit is chasing the eagle a while later, his shadow and the eagle's merge together, making Spirit appear to have wings.

Spirit:
The story that I want to tell you cannot be found in a book. They say that the history of the west was written from the saddle of a horse, but it's never been told from the heart of one. Not till now. I was born here, in this place that would come to be called the Old West. But, to my kind, the land was ageless. It had no beginning and no end, no boundary between earth and sky. Like the wind and the buffalo, we belonged here, we would always belong here. They say the mustang is the spirit of the West. Whether that west was won or lost in the end, you'll have to decide for yourself, but the story I want to tell you is true. I was there and I remember. I remember the sun, the sky, and the wind calling my name in a time when we ran free. I'll never forget the sound and the feeling of running together. The hoof beats were many, but our hearts were one."

Continuity: The apples in Spirit's pen disappear.

Written by Bryan Adams, Gretchen Peters, Hans Zimmer
Performed by Bryan Adams