Continuity mistake: At one point late in the movie, Arlene McKinney is at the kitchen sink. If you look through the window it is daylight out. She then goes outside and it is night.
Continuity mistake: When Helen Hunt is in the kitchen, while Haley Joel Osment is eating sweets for breakfast, her hair is in a mess, but in the next shot it is noticeably neater at the front.
Continuity mistake: Early in the movie after Haley Joel Osment befriends a bum they are sitting at the kitchen table and the bum pours Haley a bowl of Captain Crunch and fills it over the rim of the bowl. In the next wide shot the bowl of cereal is below the bowl's rim level as they pour milk into it.
Continuity mistake: When Trevor and his guest start on the cereal, the amount of milk in the plastic milk carton actually increases considerably between shots.
Other mistake: If you watch when Haley Joel Osment is being "stabbed" by the bullies, it is extremely obvious that the whole thing is fake. You can clearly see the knife go in under his arm. It is more visible when played in slow motion.
Continuity mistake: In the taping of Haley Joel Osment's interview, he stutters at one point, but when they replay the interview he does not stutter.
Revealing mistake: When Trevor is stabbed, we can see the knife isn't in him, it's just pressed against his shirt.
Continuity mistake: When Eugene goes to see Arlene at the casino, there is one guy with a green flower shirt who opens the door and leaves twice.
Continuity mistake: When Trevor is stabbed, lots of blood drips down his shirt, but when he's on the ground there's just a small spot of blood.
Chosen answer: The one who stabbed him was not. The others were there because they did not mean for Trevor to get stabbed and killed so now they feel guilty. They were showing Arlene they were sorry.
They were sorry for killing him.
Only one of the bullies killed him. The others were bullying, but didn't think the other would kill him. However, they still had remorse and were showing that remorse to the mother.
The one who stabbed him was probably arrested offscreen.