Opening Night is my favorite Cassavetes, and I feel it is my duty to debunk the notion that those or any of his films aside from Shadows was strictly improvised. In fact, his films were tightly scripted after actor improvisation was used to contribute to his ideas. The coherence of a film like Opening Night, the development of the themes of aging, vanity, and hope, could not just spring from the improvisational head of even the very fine actors in the movie. If you pay attention to the dialogue (outside of the lines in the play), it is obvious that much care was taken to craft them (e.g., the scene where Myrtle explains to the playwright what problems she is having with the character and script).
