Using logic to try to figure something out about a story might not make sense.

 Let's say that there's a TV show episode that ends right when an ant is about to fight a dinosaur. Using logic, you'd figure that the dinosaur would win. But seeing the next episode, you find out that despite the fact that the dinosaur should've won, it didn't.

 Since fiction can deviate from the rules of reality and its own reality, you can never use logic to prove or disprove that something that isn't proven or disproven in the story but should be the case is the case. Also, something can be proven to be the case in a story, but then not be true later in an impossible way. And something can be disproven in a story, but then become true later in an impossible way.