When Boone is tied up, his right hand is tied to his chest and his left hand is tied around his back. However, when he reaches for the knife with his right hand, you can see in the shots of his back that his right hand is tied behind his back.
When Locke is talking to Sayid in the jungle, the compass hanging from Locke's vest changes orientation from shot to shot - sometimes the front points towards the camera, sometimes the backside.
In Boone's flashback of the Sydney hotel, the image seen from the hotel window looking at the Opera House would place the hotel exactly where the Harbour Bridge is located, which is impossible.
When Locke gives Sayid the compass, Sayid sets it down next to the magnet that he was using to magnetize the needle for his own makeshift compass. The compass's proximity to the magnet would make it unusable.