When Kate finishes writing the note, she places it on the table, grabs her hat and leaves the barn (or shack). The door slams shut and the blast of air knocks the note off the table and onto the floor. Just for a brief second after the note has fallen, something that resembles a foot can be seen in the upper left-hand corner.
As the Mountain Lion is sneaking up on Shadow and Chance it is purring. Since Mountain Lions rely almost entirely on ambushing they do not purposefully make noise as this would alert the prey to its presence.