Revealing mistake: When the crew member of Expose shouts "cut," a tape marker can be seen where he stands for the shot. This could be argued that the marker is from the TV show being filmed; however, the marker is used by someone not being filmed for the TV show. (00:02:10)
Revealing mistake: 4-3: When Sayid closes the woman's eyes in the hotel room, it is clear he doesn't touch her.
Revealing mistake: Episode 4-4 "Eggtown": When Locke is in the basement hallway, he slams Ben's breakfast tray against the wall. The wall moves like it's thin plywood. Odd since basements are either thick wood or concrete over packed earth. (00:02:30)
Lighthouse - S6-E5
Revealing mistake: 6-05 - The Lighthouse: While Sawyer and Locke are climbing down the ladder, Sawyer's stunt is noticeable because his shirt's colour is different, his hair is darker, and the sweat stains on his shirt disappear.
The End (1) - S6-E17
Revealing mistake: When Desmond moves the rock, Smoke-Locke and Jack fight outside the cave while an earthquake shatters everything. Watch the leaves around and you'll notice that they don't move at all, giving away the camera effect. This also happens later on when Hugo, Ben and Jack are about to fix the cave of light.
Answer: He was eating a peice of an orange with the skin still on.
XIII