"But compared to writing a novel, where you can be God, I did the Bay of Pigs invasion in six pages once, and there were 50,000 guys with boots that I didn't have to pay, and all those extras; we didn't have to pay them"

John Sayles is comparing composing an unique to composing a screenplay. He is stating that composing a book is far more releasing than composing a screenplay since as an author, you can be God and develop whatever world you want. With a screenplay, you are restricted by the resources readily available to you. Sayles is saying that he was able to compose the Bay of Pigs invasion in six pages, but he didn't need to pay for the 50,000 bonus that would have been required to actually film it. This is a testament to the power of composing a novel, where you can develop whatever world you want without having to stress over the usefulness of recording it. Sayles is highlighting the liberty that includes composing a novel, and how it can be a lot more creative and satisfying experience than writing a screenplay.