How Do You Know if You Exist in a Simulation?

If if you could go back in time serve as a science adviser on any past science fiction film, what would it be? What would you most like to go back and tweak or correct or make a little more neuro scientifically interesting? Oh, gosh, i'd have to think about that off the top of my head. Something like the matrix is terrific. Ah, because that's an example, actually, of a piece of fiction that got body talking about this issue of, how do you like, you know, descartes said, how would i know if i'm a brain and a vat a and and i just think that i'm feeling and hearing and seeing these different things