Asked how he pulled it off, Whedon modestly took all of the credit.
"I did so much work, certainly nobody at Marvel had anything to do with it," he joked.
Whedon admitted that he advised Marvel not to make the announcement if they couldn't coordinate everyone. "I even said, 'Don't do it if we can't make the deal with these actors.' I desperately wanted this exact crew for the movie and we didn't know until [Saturday] morning that it was going to happen, and that's because of the extraordinarily hard work and trust from people who aren't me."
Whedon added that being surrounded by his new cast was a little bit overwhelming, especially since that Marvel panel marked the first time all of the castmates had been assembled in one room.
"The energy is extraordinary," Whedon said of his actors. "This is an extremely collaborative, supportive intelligent cast; they're very sweet. They're not challenging each other, they're there just enjoying each other and ready to get into it. And that's an exciting atmosphere."