Plot hole: When Alex and Clear are sitting and having coffee they are on a corner. He looks in the window to see the bus pass, and as he looks to see if it is there, it's not. As the camera pans across the street, there is some construction going on which is blocking that whole road from being used, but then Terry, Carter's girlfriend gets "waxed" by the bus - no way it could have got through all that construction.
Plot hole: It has already been mentioned that a certain shot reveals that Sidney isn't wearing the bullet-proof vest when she should be. Further to this, most of the shots in the climax sequence make it impossible for her to be wearing one, as you can see the contours of her chest throughout. A bullet-proof vest would flatten the appearance of this.
Plot hole: When Wolf and Tony find Virginia in the Huntsman's tree house, she tells them that he chained her up, so she can't go downstairs and open the door from the inside. However, after Wolf climbs her hair and enters through the window, the two of them walk down the stairs without any chains stopping her. They couldn't have cut her free with the magic ax because Tony was holding it, and he was downstairs by the door.
Plot hole: Referring to that blackout night. How come the group can actually film how they put all their cameras and stuff into its hide?
Plot hole: After Nanahara and Noriko run away from Akamatsu at the school, Niida shows up from behind some bushes opposite the school and inadvertently kills Akamatsu with his crossbow. But Niida is Boy 16, which means he should still be in the school building (he's supposed to come out after Noriko, who's Girl 15). There's no way he has any time to get into those bushes.
Plot hole: In the cafe scene after the fingerprints have been identified as belonging to someone who was thought to have been killed, Jean Reno tells Vincent Cassel that the person who shot at him had all ten fingers. How did he know that? The audience only sees one hand which is holding the pistol and the other hand is out of sight.
Plot hole: Towards the end we see Jones ring Derrick to warn him that Travis has a gun - why would she do this if it's all planned? why risk him picking the phone up? he would have escaped before Travis had time to stop him and get him back inside to finish the set up. This scene is purely for the audience to be more taken in and shocked at the actually twist. (01:17:00)
Plot hole: Just before playing the water glasses, Gracie plays a couple notes, one of which is very high. She drinks some water out of the glass to lower the pitch. The problem is that the pitch goes up when you remove water from the glass, not down. Drinking out of the glass would've made the note sound higher. Some people and websites will make you believe that the pitch is going down due to an increase in the size of the resonant chamber but singing glasses have nothing to do with cavity resonance. Glass singing is caused by the molecules in the glass vibrating in resonance with each other. More water dampens the motion, slowing it down and lowering the pitch. Some of the confusion comes from schools not teaching children that liquids and gasses are both fluids. In the case of water in glasses, the water is not changing the cavity as much as one thinks, just damping it. And finally, if you don't believe me, don't Google it, try it.