Cabin Fever - S4-E11
Continuity mistake: In the scene just after John Locke's teenage mother runs from the hospital room, the nurse converses with the grandmother. You can see her put a cigarette to her mouth with visible lipstick stains on the wrong end of the cigarette, possibly from previous takes. (00:32:10)
Answer: He was eating a peice of an orange with the skin still on.
XIII