Revealing mistake: When William is running at the end, there is already a blood trail on the floor. Clearly from another take. (01:15:10)
Revealing mistake: When Eddie is cutting the stomach flesh, there is a point where if you look carefully, you can see the outline of the fake flesh. (00:03:50)
Revealing mistake: There is one shot of Simone cutting off her arm where you can see it is a fake arm. It's noticeable by the change in colour. (00:04:50)
Revealing mistake: In the opening game, the same shot of the needle moving on the scale is used twice when Eddie drops some flesh onto the scales. (00:05:25)
Revealing mistake: When Hoffman strikes the matches, he throws them in the petrol. However, if you look carefully you can see they are not lit when Hoffman throws them. (01:10:30)
Chosen answer: It's possible, but unlikely. 1) She was under great distress and might not have thought of that. 2) It would be easier (and more importantly, quicker) to cut through Easton's soft skin than the spear. 3) There is a good chance that tampering with the spear might have made it go off.
TedStixon