When Dave Bautista found out he got the role of Drax the Destroyer, he broke down in tears, overjoyed at getting a Marvel comic book role. He prepared for the role with an acting coach.
Vin Diesel recorded all his lines in several different languages, including Russian, Mandarin, Spanish, Portuguese, German, and French, so that they could use his real voice in the film around the world.
Chris Pratt apparently stole his Star-Lord costume from the set, for the sole purpose of having it available so he could show up in costume to visit sick children in the hospital, who might want to meet Star-Lord.
James Gunn stated that Chris Pratt's audition was so good, he was prepared to offer him the role, even if Pratt did not lose weight, or get in shape in time. Gunn joked that he was willing to CGI a six-pack on Pratt's body. However, Pratt asked Gunn to give him six months to lose fifty pounds, and he ended up losing sixty.
According to Vin Diesel, his performance as Groot helped him through a dark time in his life. He was dealing with the loss of his best friend and "Fast and Furious" co-star Paul Walker: "It was the first time I came back to dealing with human beings after dealing with death, so playing a character who celebrates life in the way Groot does, was very nice."
Rob Zombie: Ravager navigator. Zombie always appears in movies by James Gunn albeit in voice cameos only.