Complex sentence: When the film is shown, the press, cast and crew discover that Weidmann junked the script; he made a "reality movie", composed of footage shot making the film (most without the actors' knowledge).
Split into simpler sentences: When the film is shown, the press, cast and crew discover that Weidmann junked the script. He made a "reality movie", composed of footage shot making the film (most without the actors' knowledge).