If an actor disagrees with the director's note, the rule is to try it once and see how it goes. Once you've done that, you can toss out additional ideas or expand on it, but you have to at least do it once.

If the actor simply wants to give the director or other actors general notes that they aren't immediately involved in, the answer is "no way." The director was hired to shape the overall vision of the show. However, that's not to say that they are infallible. Good directors will generally ask people they trust to come in and watch the show and give feedback. The Artistic Director (the director's boss) will also usually give feedback.

And ultimately, directors get reputations. Actors can choose who they want to work with and theatre communities are small. Just a few months back I watched a director get fired and completely ostracized because she was downright mean when it came to giving feedback. She would use insults and fear to control actors. I doubt she will ever work in this area again.