Continuity mistake: Evan throws spaghetti out the window and a few are stuck to the pan. They disappear seconds later.
Continuity mistake: Isabella's photo that they look up on the computer is in her jail cell, which comes later in the film.
Revealing mistake: Widescreen. When Rory gets sliced in thirds, the bottom of his legs are not visible: the grass cuts through his legs. Post Production forgot about John Cherry's legs.
Continuity mistake: When all the survivors are leaving the police station, you can see their reflections in the two-way mirror. Before they cut to they mirror, Timmy's mom says, "Let's go" and starts to get up. But in the reflection, she is still sitting. Cut back to them and she is just getting up again. Also in the reflection, the young lady who was on her cell phone in the crash is getting up to leave; then they cut to the group and she is getting up again.
Other mistake: Kat is trapped by the log and the car door is closed. When she drops the cigarette it looks as if the door is off, and she could get out.
Chosen answer: Eugene's death had no clues I know of, but Clear and Rory's did, Rory's clue was with Nora's. The trophy's shadow is segmented, giving it a divided look, Rory ends up divided to pieces by the barbed fence. As for Clear, Bludworth hints at it with his comment "such fire you have now".