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.
Other mistake: When Kimberly gets in the ambulance at the hospital to drive it into the lake she shifts it upward instead of downward to go from park to reverse.
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".