FAQ for
Dalkomhan insaeng (2005) More at IMDbPro »

In the last scene we see Sun-Woo sipping on an espresso and mock fighting with his reflection like Moon-Suk mimicked and jibed at earlier, and the voice over tells us more of the young prophet, saying he had a most beautiful dream but woke up in tears, and when asked by his mentor why he sobbed so, he said it was because the dream was so beautiful that he knew it could never come true.

By taking careful note of both that dialogue and the environment Sun-Woo is in here -- sipping on an espresso looking out over the city, like right at the start of the film -- we can theorise that the somewhat unrealistic nature of the last two hours is very unlikely and the entire film could have been thought out in Sun-Woos head -- he is, after all, a cool calculated hitman for the mob -- and what we have just witnessed is merely a collection of apparitions of what Sun-Woo surmises will occur if he doesnt follow through with his orders. Realise just how overtly heroic he appears? It could be his imagination running wild. And the prophets' words are there to back this up, maybe. Or it could just be a genuine flashback to a happier, simple time for our protagonist, while he waits at deaths door in reality, to calm the audience somewhat after his death. In the end the choice is yours.