As I suspected, everyone was inoculated before being exposed to the virus, thus saving them from being infected. Yes, it's a cheat, but it's expected. As for the showdown between Oliver and Ra al Ghul, it was decent. It was nowhere near the epic showdown between Oliver and Deathstroke last season. I will say that I was somewhat surprised that they actually had Oliver kill off Ra al Ghul, even if it was expected. Loved seeing Felicity wearing the ATOM suit. Interesting twist at the end showing Merlyn as the new Ra al Ghul. Was kind of hoping to see him resurrect Sara in the Pit as the cliffhanger. It would have been appropriate given Nyssa was right there and would have been the ultimate peace offering to secure her loyalty. Anyway, Oliver "retiring" from Arrow is not going to happen. Duh. Nice to finally see Thea as  Speedy become a characters on the show, using Roy's old Red Arrow costume. Overall, a solid Season Finale.