Ok, so nothing looks wrong to you (unless you know me and my 'children')
If you guess the donkey, you'd be correct! Go back to the first picture and notice that she somehow, magically, got herself successfully out of her pasture with Romeo and into the neighboring pasture with the big horses, Apollo & Gypsy.
I normally do not let the little ones run with the big ones just because when they get wound up and rambunctious and start throwing play bucks, one kick from Apollo on one of my little ones and that could be it! I just don't take the chance.....although clearly, there doesn't seem to be any concern that there is a little donkey hiding in the tall brush in picture #1!