Michael Clayton is an in-house "fixer" at one of the largest corporate law firms in New York. A former criminal prosecutor, Clayton takes care of Kenner, Bach and Ledeen's dirtiest work at the behest of the firm's co-founder Marty Bach. Though burned out and hardly content with his job as a fixer, his divorce, a failed business venture and mounting debt have left Clayton inextricably tied to the firm. At U/North, meanwhile, the career of litigator Karen Crowder rests on the multi-million dollar settlement of a class action suit that Clayton's firm is leading to a seemingly successful conclusion. But when Kenner Bach's brilliant and guilt-ridden attorney Arthur Edens sabotages the U/North case, Clayton faces the biggest challenge of his career and his life.

It looks like people either hated or loved this movie. I thought it was pretty good but I don't understand where the horses came from and why he just randomly pulls off the side of the road and gets out? Did I miss something in the movie?

I believe they came from when he was flipping through the red book in Arthur's apartment. There was a page in the book, that had a horse standing in between two trees. In the book it was only one horse, but i am assuming that is where it came from.