The interesting philosophy I remember most about the book and the movie is trying to determine who is crazy and who is sane? What is "prison" and what is "freedom"? Who is in control and who isn't?
In the final scene the Chief (pretending to be deaf and dumb) leaves the Mental Ward and it's up to you to decide, based on the outcomes of all the characters, who is better off.
So what was my point as the three departing Board members left me with yet another term?
Depends on your perspective :)