When "Locke" smashes the phone Zoe gives him, the butt of his staff clearly misses the phone by several inches before the camera cuts to a close-up of the splintering device.
Jack's chat with the Man in Black-and later with Claire-takes place at night. They come back from the chat in bright daylight.
39:40 in - When Sawyer and gang (less Jack) reach Hydra Island in the sailboat, it's the same filmed location of when Sawyer and Kate leave the main island earlier in the episode. The sailboat is actually shown anchored in the exact same spot.
At 24:30 in, Sawyer and Kate enter the water to swim to the sailboat. However, there's at least a 35 - 40 foot rock peninsula just to their left. Walking out on the rocks and then entering the water would have made for a much shorter and easier swim.
When Zoe speaks to Locke and the surrounding others raise their rifles, various racking sounds are heard, although only few of them actually rack their rifle. It would be illogical anyway to wait with loading the first round into the chamber until raising the weapon. The racking sounds are only added for dramatic purposes.
After the rocket hits the beach, Jack's face and neck are covered with sand, dirt and blood. After he is carried a few yards away by Locke and propped up against the tree, his face and neck have barely anything on it.