The word “reshoots” has become a troubling word to have associated with larger films. There are plenty of conflicting reports on how reshoots changed Suicide Squad, or the various rumors swirling around Rogue One: A Star Wars Story and its reshoots. In the case of Guardians of the Galaxy Vol. 2, however, the reshoots are likely nothing to worry about, making it a situation similar to the recently announced reshoots DC Comics’ Wonder Woman is undergoing.
Marvel (and many other larger studios) schedule in dates for reshoots before filming even begins. As such, it’s likely not a cause for concern but rather an opportunity for the filmmakers to further improve upon their projects. James Gunn has already undertaken the task of editing the sequel and most likely has found a few things that he thinks could be added or changed for the better. If this is the case, then it is exactly why studios schedule dates for reshoot in advance. Besides, the film is over five months away from hitting theaters, which gives Gunn and co. plenty of time to incorporate the new material, and get the film exactly as they want it.
Source: Karen Gillan