When Charlie and Hurley are questioning Jack about the water in the tent, two people, a man and woman, walk behind Jack twice in the same direction.
Right after Locke goes to search for water, the camera cuts to Jack running through the woods after he sees his father. Jack has two pairs of cuts on his face from the crash: one on his left temple, the other on his right cheek. During this sequence, there is a shot where Jack turns to reveal cuts on his right temple, a minor flip in the editing process.
(About 36 minutes in) A suitcase behind Jack has something about the size of a baseball on it fully engulfed in flames. After he puts the torch down, the fire is gone. The same thing happens a moment later when he opens and re-closes the casket lid.
When Boone is drowning in the water, Charlie claims he can't swim and calls to Jack for help. Later, in the season 3 finale, Charlie recounts that he was a school swimming champion and makes a rather lengthy swim into the underwater DHARMA station, The Looking Glass. However, this just means that Charlie lied about his inability to swim in the pilot.
At one point you can see Jack standing near a fire, and he hears somebody walk behind him. He grabs a piece of wood from the fire and goes to follow that person. In later shots you can see fire "dripping" from the wood, just like from a real torch, thus indicating that it was lit with oil - something he couldn't have found in the woods.
When Jack removes his shirt as he enters the water to save the drowning woman, there is no sign of the wound on the left side of his back which Kate sewed up in the pilot.
When Jack is standing at the beach talking to Kate and seeing his father standing in the sea, a grey fence can be seen in the bushes on the beach, on the left side of the frame.
While Claire is lying down, just after she says, "Our only hunter's gonna get eaten so he can get the pregnant girl some more water," we hear Charlie say, "I wouldn't worry about that," but his lips just begin to open mid-sentence, and he certainly doesn't say that.
When Jack is precariously hanging over the cliff, the thick safety wire attached to the front of Jack's waistband is quite visible in a few shots, as he moves about. One such instance is two shots after Locke says, " Take my hand."
When Jack enters the water to try and save the woman who is drowning, in the shot that shows him swimming towards the camera a jet ski or boat keel trail is clearly visible.
(At 21.14) When Locke is reaching out for Jack hanging from the cliff, you can see the boom mic come into shot at the top of the screen.