Revealing mistake: When Goodwin and Ana Lucia sits down to have a break and Goodwin hands over some fruit to Ana, she says "Where do you think they got it? I mean they're not even wearing shoes", directing to the knife. If you watch in the background you can see a car driving.
Continuity mistake: Ana-Lucia says that she never saw Nathan during the two hours the plane was in the air, which Cindy the flight-attendant agrees with, saying that she has a photographic memory for passengers. But the plane was actually in the air for eight hours before the crash, as revealed in the pilot, so, not only should Cindy remember him after that long, but they all should be able to tell the difference between two and eight hours.