In the episode that re-aired 8/24/05, there's a scene with the Korean couple alone in which Sun switched mid-dialog from Korean to English, then back to Korean after a few sentences. When she switched to English, there was a reaction shot of Jin -- a turnaround "take".

Are we to understand she was speaking English to him during that scene? Or are we to take it as dramatic license, that for some reason someone thought Korean with English subtitles just didn't cut it for those lines, and that we're supposed to understand Jin heard it all in Korean?

It makes a difference how "literally" we can take scenes in Lost in general. The same episode played some other "tricks" with the sound track that tended to give the audience doubts as to whether what we're hearing is what the characters are hearing or just part of the mood music. When the fire broke out, there was an alarm bell on the sound track that faded into the music, as if to fool us for a second into thinking the characters had a fire alarm. Then there was the scene where Hugo's CD stopped playing, making us think the opposite -- that it was just mood music, but turned out to be what a character was hearing. So that called the whole Korean-English-Korean bit, and Jin's rxn, into question.

This is akin to the question I asked before about whether the sound track was "fair" w.r.t. the apparent mechanical SFX of John Locke's being dragged.

Best Wishes,
Suds