The End (1) - S6-E17
Audio problem: When Desmond, Locke and Jack are standing outside the cave with light, Desmond says "maybe I can find a way out for you too," or something like that. Jack replies, "there are no do-overs." The camera then goes to over Jack's right shoulder as he says, "I tried that once." However, the words don't match what his mouth is saying.
Answer: He was eating a peice of an orange with the skin still on.
XIII