Vệ binh dải Ngân Hà 3
Sản xuất > Pre-production

Pre-production work creating the designs and visuals for the film began by April 2021. In early May, Marvel Studios announced that the film would be released on May 5, 2023. Later that month, Gunn said Vol. 3 would take place after the events of Thor: Love and Thunder (2022), which features several Guardians characters. That film concludes the storyline established in Endgame which sees Thor journey off with the Guardians. Gunn noted this ending was decided upon "in editing" and conflicted with his already-submitted screenplay for Vol. 3, since he never planned to feature Thor in the film. Gunn had begun storyboarding the film by June, with filming later revealed to begin in November 2021 in Atlanta, Georgia for an expected end around April 2022. By then, Bautista said he had not read a script for Vol. 3 and was unsure if it had changed during the production delays. The next month, Gillan said that she and Klementieff had read the script together and she found it to be incredible, brilliant, emotional, and funny. She also felt it was Gunn's "strongest work yet" with the Guardians characters. Gunn reiterated that the script had "basically stayed the same" from three years prior but he had been "playing with it in little ways" over the years. He was in the middle of another draft by the end of the month and said the film would be emotional and have a "heavier" story than the previous films, with a more grounded approach that was inspired by The Suicide Squad and Peacemaker. Gunn originally wrote a cameo appearance for Kumail Nanjiani, a friend of his, but removed this after learning Nanjiani was cast as Kingo in Marvel Studios' Eternals (2021).
By late August, Gunn and Marvel Studios began meeting with actors for the role of Adam Warlock, including Will Poulter. George MacKay was also on the shortlist and Regé-Jean Page was considered for the part. Poulter auditioned for the role over Zoom before an in-person screen test with Gunn in Atlanta. When first auditioning for Warlock, Poulter was unaware of who his character's name was other than he had been teased at the post-credits scene of Vol. 2, but Marvel just described the role to him as "an untitled character" until Poulter was "drip-fed" with more information over and over until discovering how steeped Adam Warlock is in the source material. In September, Gillan reiterated her positive comments about the script and said the film would explore the characters from the previous Guardians films on a deeper level, while Seth Green, who voices Howard the Duck in the MCU, said the film would be about Gamora and Nebula's story. He did not know at that time if Howard would appear after doing so in the previous Guardians films. Poulter was cast as Adam Warlock in October, and Gunn said "dozens of roles" had already been cast. Poulter was chosen for the part because of his dramatic and comedic abilities and because Gunn "wanted somebody who was youthful" and would fit with Marvel Studios' future plans for the character. Casting also took place for various background roles, including aliens and security guards. Pratt began rehearsals and camera tests later that month, and a production meeting was held in early November, shortly before the start of filming. Gunn also reiterated his comments on not resurrecting Yondu in the film.