Sean Gunn believes the Guardians of the Galaxy Vol. 3 script might get a touch up before production begins. This is a common occurrence in the entertainment industry and James Gunn may have some better ideas after seeing the final cut of Avengers: Endgame on the big screen. His version of the script has been complete for over a year, so it would make sense he would want to go back and do some revisions to make things a bit tighter or to add some new jokes or references.
Sean Gunn hasn't read the original Guardians of the Galaxy Vol. 3 script but says, "I know, you know... I think my brother may do... he may do another pass, in which case I would read that version." All of the major plot points for Avengers: Endgame had been laid out years ahead of time and James Gunn was fully aware of everything he needed to make the third and final movie in the trilogy. So, it seems highly unlikely that Gunn would go back to make some major changes. He could go back to add some extremely obscure Easter Eggs to taunt fans with for years to come, which would make sense.
Had James Gunn not been fired from Guardians of the Galaxy Vol. 3 last summer, the principle photography probably would have wrapped by this time. The production was all set to begin early this year. In the time it took for Disney to fire and then rehire Gunn, he signed on to write and direct The Suicide Squad for DC. So, that movie will be coming next and then work will begin on the next Guardians chapter. While Sean Gunn hasn't read the Guardians script, he has read The Suicide Squad screenplay and thinks it's great.
Production is preparing to begin for The Suicide Squad and James Gunn is excited to get moving on it. The director has taken some of his Marvel Studios tricks with him and is making sure nothing about the movie leaks to the public, so the upcoming movie is very much a mystery at this point in time, except for some of the officially confirmed cast members. When asked if he had a part, Sean Gunn shied away from answering the question head on. However, he has read the script and his brother is directing, meaning he'll at the very least probably have a cameo.
Marvel Cinematic Universe fans were ecstatic to hear that Disney had rehired James Gunn to direct Guardians of the Galaxy Vol. 3. While some script tweaking is almost always necessary, too much could end up being a bad thing, so we'll have to wait and see. Let's just hope Gunn isn't rewriting the script on the set because that almost always spells disaster for a movie. The interview with Sean Gunn was originally conducted by Comic Book.