In the scene up in the boys room, after Billy declares that he doesn't want to go through with his plan, the older boys are all standing in a group with the younger two sitting on the floor. Now the camera shot changes from the whole group to a close up of the boys on the floor several times. Watch when they do. From the shot of the whole group all the boys are standing around in their underwear, but when we close in on the boys on the floor the boy standing in the shot next to them is clearly wearing jeans. This can be seen just about every time this shot change is made. Once I saw this it was so obvious, a pretty big mistake in my book!