Off-screen heroes reveal Marvel magic
Who could follow The Avengers' success?
The first instalment was one of Marvel's most successful films, making more than $771m (£540m) at the worldwide box office.
Gunn has also worked on the hugely-successful Avengers franchise.
There has been no immediate response from the filmmaker, but in a series of tweets posted on Thursday he addressed the controversy surrounding his old posts.
"I viewed myself as a provocateur, making movies and telling jokes that were outrageous and taboo," he said. "I am very, very different than I was a few years ago."