Matthew Vaughn is the man credited for saving the X-Men franchise after The Last Stand, and while he would choose to helm Kingsman: The Secret Service instead of returning for X-Men: Apocalypse, the X-Men: First Class helmer has continued to be at least somewhat involved with Fox's Marvel movies. Fantastic Four is part of that deal. However, one very interesting rumour which recently started doing the rounds is that Vaughn was brought in to take over from Trank when the time came for reshoots (which, depending on who you believe, were either something of nothing or extensive enough to dramatically change the movie). Trank would quickly take to Twitter to deny this report. Fox would face trouble with the Directors Guild of America if it was true, so chances are Vaughn didn't insert himself into the production in such a major way. Even so, some rumours have pointed to Simon Kinberg and Hutch Parker stepping in to try and salvage the film at this point, so it's likely that Trank didn't have a ton of control during reshoots.
