It is impossible to vote illegally in the state of Michigan, imo. I don't know how anyone could manage it unless the polling folk were in on it. I suppose that could happen in Macomb county...hard to say.
You must be registered. And you must show your drivers license.
Just to add that moving here from Washington state almost 4 years ago was the most frustrating thing in terms of document requirements.
This state does not mess around when it comes to any kind of registraion.