With the film now planning a Michigan shoot, Zack Snyder’s still-untitled Superman/Batman film is racing through pre-production.

“One of the things that has been fun for us,” screenwriter David S. Goyer tells The Associated Press (via Comic Book Therapy), “is we’re a bit a further along than what I think people realize.”

The Man of Steel sequel is already set to feature the return of Henry Cavill, Amy Adams, Diane Lane and Laurence Fishburne with Ben Affleck making his debut as Batman/Bruce Wayne. Although Affleck’s casting last month set internet message boards on fire, Goyer notes that it’s important to not be swayed by fan criticism.

“From a fan point of view, we’re conscious of that when you’re working on these things, but you can’t let yourself be paralyzed by that,” he says. “At the end of the day, you still have to create something. And if you try and think, ‘Well what would the fans like?’ then you stop being creative. It’s sort of like, ‘Where does it end?’ You have to write the story that you want to write, and hope that people want to see it.”

So who does Goyer side with when and if it comes down to the Dark Knight and the Man of Steel going mano a mano?

“Most comic book purists would say Batman,” he says, “because he is the ultimate strategist. Even though it makes no sense whatsoever. If Superman just flicked his finger, Batman would be done for.”

Batman/Superman hits the big screen July 17, 2015.