[From
here.]
Upon stepping through the door, Zack had suddenly felt kind of dizzy, almost like the floor was falling out on him. He didn't know what that was about, but he didn't even get the chance to try and come up with a reason for it, since the next thing he knew he was being overwhelmed by a whole new set of sensations. First of all, he was very much not in a file room. His stomach lurched as his body was tossed violently, and he was overtaken by a jarring pain as his side connected with the railing of--
An airship?! That explained the movement, and when Zack turned his head slightly, he realized that it was airborne. Solid ground was way, way down there. "Whoooa," he yelped as he pulled himself away from the edge of the deck. He stumbled forward and that was when the rest of it connected: first of all, he had a burst of energy that made it pretty clear that he was back in tip-top shape. The mako was working, unhindered by the institute. (Big guess as to why!) Secondly, he was back in his First Class uniform and had none other than the Buster Sword strapped to his back.
He glanced over to Cloud and Yuffie, who were nearby and also back in their normal clothing -- or what was normal for them in their time, at least. Wait a second; why was Cloud wearing...? Oh, it didn't matter now!
"What the hell just happened?!" he blurted out, fighting to keep his balance as the airship jerked around unpredictably. They were home, that much was clear. This was the Highwind he'd seen docked in Junon, but he'd certainly never been on it himself. Hopefully either Cloud or Yuffie could shed some light on the situation, since he was at a complete loss.