Big-Lipped Alligator Moment: The man who appears to have cerebral palsy and hangs out around the river bank. It's never really addressed who the heck he is or why he's there.
Jerkass Woobie: The three main charcters: Dong-jin, Ryu and Yeong-mi. Apparently, their misery is all because of their own actions, which is what started the Cycle of Revenge in the first place.
Moral Event Horizon: The main character, Dong-jin himself crosses this when he tortures Yeong-mi to death, thereby showing that he's really no better than the kidnappers. And if that wasn't enough, it's also revealed that he also killed the delivery boy who delivered the noodles to Yeong-mi's house, because said guy may or may not be a witness to Dong-jin's crime.