"The dreams were not an executive favorite either — the dreams, the farmhouse, these were things I fought to keep," Whedon said. "With the cave, it really turned into: They pointed a gun at the farm's head and said, 'Give us the cave, or we'll take out the farm' — in a civilized way. I respect these guys, they're artists, but that's when it got really, really unpleasant."

Whedon explained that there was additional footage shot in the cave, but much of it was cut, as test audiences didn't respond to it. He said there was even a point at which studio notes led to the cave sequence getting excised completely: "I was so beaten down at that point that I was like, 'Sure, OK — what movie is this?' And the editors were like, 'No. You have to show the [events in the cave]. You can't just say it.' "

Whedon also wanted Captain Marvel and Spider-Man to appear toward the end of the film, but alas, business got in the way, as Marvel and Sony didn't agree to team on the Spider-Man franchise until February. Additionally, Captain Marvel has yet to be cast. "I would have put both of them [in Ultron], but neither of the deals were made," Whedon said about the characters.

Email: Ryan.Gajewski@THR.com

Twitter: @_RyanGajewski