Okay, so everyone at work is talking about The Corporation lately, so, as the local representative of the local corporation, I might as well throw in my two cents.
There are two important things to understand about this documentary. First, it offers no evidence for any of its claims; its examples are standalone examples, easily countered by hundreds of examples of non-evil corporations that didn't do any of those things. Of course, the movie doesn't claim to be making claims; it's offering facts. It's just that they expect you to make certain conclusions from their set of facts, and you shouldn't, because there is no logical way to get from those facts to those conclusions. A implies B, but that doesn't mean that whenever B is true, A is true. Don't be confused! So my first point is that this movie is deliberately controversial in order to encourage conversation. You can't learn anything useful from the documentary itself, only from the conversations it causes.
Secondly, they horribly confuse morality and legality. The two are related, but not the same. Corporations are "people" from the point of view of the law; the "owners" of corporations are legally protected (for certain purposes), because the corporation takes the legal blame. Okay, yes, and there are lots of good reasons for this. But people take this one step further, and say that corporations are immoral or amoral because they (and their owners) don't have to take responsibility for their actions.
Wow! Stop! If I'm running a company, and my company does something against my moral standards, then I take moral responsibility. Morality isn't about punishment; it's about my conscience. I will (or should) feel just as bad whether I do something evil or whether I paid someone to do something evil at my request. If people running companies are immoral, don't blame the companies; blame the people.
As a person, I can do lots of immoral things that aren't legally punishable. These are the exact same things that corporations can do without being punished. On the other hand, if a corporation does illegal things, it can be sued, fined, imprisoned (legal sanctions), or put to death (shut down) - just like me.
Lots of corporations do lots of evil things, but don't be blinded into thinking this happens because of some unrelated laws that treat corporations like people. Corporations do evil things for exactly one reason - they're run by evil people. Fix the people, and you'll fix the corporations. Or make enforceable laws about specific evil things, and the corporations, like people, will have to comply.