The Russo Brothers shot Avengers: Infinity War and Avengers 4 back-to-back but there's still plenty of work to be done for the next Avengers film, according to Mark "loose lips" Ruffalo.

"Well we're doing re-shoots starting in September," he said around the hour mark on The Marvelists podcast. "Then you guys will get the second installment. Which we don't even know what it's gonna be yet. We're not just doing re-shoots, we're going to finish the movie, which we really didn't get to finish totally when we left it last year."

But it won't be just the typical re-shoots. Ruffalo says they are entirely revamping some of the scenes—sometimes right after they've filmed it.

"I don't even know that they really know exactly," said Ruffalo, referring to the Avengers 4 creative team. "Some of it is happening while we're there. It's pretty amazing. And we'll shoot some stuff and a few days later come back and re-shoot it cause we wanna take it in another direction. It's a very living organism, even as we approach it being a locked picture, we're still working on it."

But Ruffalo was careful not to give spoilers on what happens next. When the podcasters pressed him for his plans after Avengers 4, he refused to say. "Yeah, I don't know. I have no idea," he said.

Either way, movie-watchers will see what happens next soon enough as Avengers 4, which has yet to be co-titled, is slated to arrive in theaters on May 4, 2019.