Continuity mistake: When Boone is tied up with his right arm in front and his left arm at his back, just after Locke leaves, Boone tries to lean over to reach the knife. However, in the close-up of his back, it's his right arm that is tied behind him. The same flipped shot is used later, three more times, when he "hears" Shannon scream.
Revealing mistake: In Boone's flashback in the hotel, you can see the Sydney Opera House out the window which looks nice, except that in order to see the it from that perspective the hotel would need to be EXACTLY where the Harbour Bridge is, but there are no hotels in Sydney that could provide this angle of view.
Continuity mistake: When Boone is tied up, with the goo in his hair, Locke has only his backpack slung over his left shoulder, when he holds the sheath in his left hand as he raises his right arm to throw the knife. After a brief cut to shocked Boone, Locke is in mid-throw and suddenly his second bag is slung diagonally across his chest and shoulder.
Continuity mistake: When Sayid opens the lid of the compass to show Jack, in the close-up, all of Sayid's fingernails are short and trimmed, yet, in previous and following shots (including next episode "Special") some of his fingernails (such as the thumbs) are very long again. This occurs in many other episodes, such as "Exodus 2".