Continuity mistake: In the scene where Sawyer collapses from his bullet wound, he collapses onto his knees and then twists so that his good arm is towards the ground. From there, he rolls to his back. Then the camera angle changes so we're looking at Michael and Jin running towards Sawyer from the front. Sawyer is now on his good arm's side.
Continuity mistake: When Jack shows Locke the suitcase full of guns, you can see a stick visible in Locke's right hand. However, when Jack asks if Locke knows how to use a gun, you can see that after the camera has panned around, Locke is now holding the gun with both hands, with the stick nowhere to be seen.
Continuity mistake: After Sawyer admits to Kate that he doesn't have the inhalers, Sayid and he get into a tussle. In the first shot, the back of Sayid's white shirt is fairly clean as he is standing, but in the next wider shot the back is completely filthy - before he and Sawyer ever even hit the ground.
Visible crew/equipment: When Sawyer finds his blue tarp that the boar ran off with earlier, Sawyer hears the whispers, then the boar reappears and chases him. When the mean old boar flips Sawyer over, the chain link fence (used for the stunt) is clearly visible beyond the grass, at the top right corner of the screen. (Also seen on Disc 7.)
Continuity mistake: At Essam's place, when Sayid walks toward the smoke alarm he places his tall glass mug with tea on the coffee table. When he drops the "bug" into the tea, in the close-up it is a different glass mug - note the style.
Continuity mistake: When Michael sits with Walt at the airport, Michael says, "If you're worried about Vincent," and the newspaper in his hands is folded and held straight up with the blue Oceanic envelope. Yet, when he says, "Dogs fly in the luggage compartment all the time," the newspaper is sideways and there is no blue envelope.
Continuity mistake: When Jack is packing water bottles in to the sack and Locke says "I think one of us should stay and help Charlie salvage the wreckage", you see Jack putting a bottle in to the sack. His hands are now empty, but when it cuts he suddenly has a new bottle in his hand which he puts in to the sack.
Continuity mistake: When Locke is about to leave to go search for Claire and Charlie, Michael stops him to talk. Locke throws the backpack over his right shoulder, but in the next close-up it's swung over his left (not a flipped shot).