I just watched this film. The beginning was good for the history (plot) of the rest of the movie but felt like it didn’t really fit, but the rest of the movie was great. I watched the outtakes and bloopers at the end, and you were right, there were medics and doctors everywhere fixing people up.
There are a lot of great fight scenes, and a few touching moments. I’m glad I was finally able to watch it.
Also, I don’t think it’s a Korean film… Found a Wiki for it, it’s a Thai film.