Continuity mistake: When they are approaching the plane, Sawyer is in the front and it appears as if Sayid grabs Claire's hand. In the next shot Sawyer is next to Sayid and Claire. (00:15:55)
Continuity mistake: After the submarine sinks, Jack lays Sawyer on the sand. In the last angle his head swaps from facing sideways to up.
Continuity mistake: When Jack and Claire open the music box, from the back angles their heads are almost touching each other, but from the front angles it's noticeable that both guys are sitting wider apart.
Continuity mistake: After the submarine sinks, Jack is in the beach hugging Kate and a strand of wet hair is on his forehead. When the angle changes the hairstyle has changed and his forehead appears clear.
Continuity mistake: When the Smoke smashes the armed guard against the cage he lies unconscious with his left arm stretched out. A frame later, from another angle, the arm rests by his side.
Answer: He was eating a peice of an orange with the skin still on.
XIII