Filmmaker Christopher McQuarrie is prolific on Twitter, often engaging with fans and offering pieces of tough love and behind-the-scenes advice. Does the fact that he's writing and directing the upcoming Mission: Impossible sequels, both 7 and 8, limit his use of Twitter? Not so much. In fact, the director, who previously helmed the acclaimed Rogue Nation and Fallout installments of the Tom Cruise action franchise, recently revealed which key creative member will be returning to the production of 7 and 8 thanks to his handy Twitter account. In the Fallout home video special features, McQuarrie and that …