Via Comicbook.com:

Even the people who didn’t love Rogue One: A Star Wars Story left the theater feeling exhilirated, thanks to the final sequence featuring none other than Darth Vader. In a vicious and violent moment, Vader shows the true power of the dark side of the Force, deflecting blaster bolts, slashing, Force choking, and stabbing his way through Rebel soldiers like nothing.

While Vader’s presence, and the idea of a hard copy of the Death Star plans being handed off to Leia were both in the initial concept of the closing moments of the film, the dark side rampage was a late add.

“It was a fantastic add – the Vader action scene, with him boarding the ship and dispatching all those rebel soldiers. That was something conceptualized a little later,” editor John Gilroy, who joined the project toward the end of the reshoots, told Yahoo! Movies. “The main structure was there,” he clarified, but the actual Vader, going through the air lock and trying to get to the shuttle Star Wars fans know is the Tantive IV, moment was new.

“It was a really great punch in the arm and something I think fans wanted to see,” Gilroy said.

That also explains why two actors are credited as portraying Darth Vader in the suit – Spencer Wilding did all the original scenes, while Daniel Naprous was brought in for the action sequence, purely due to the timing of the additional shots.

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