When the six survivors of the plane crash have to wade through a shallow tributary of Amazon river, China (Andy Silas) is attacked by Piranhas who bite off the flesh of his right lower leg - Kevin (Michael Sopkiw) jumps to him and saves his life. Captain Heinz (Milton Rodríguez) kills the mutilated China - who from his point of view only represents an impediment to their escape from the jungle - by spearing him with his machete from back through thorax and throws him back into the water that one minute ago has been teemed with a hungry Piranha swarm, but: None of the killerfish shows up now to devour on the freshly killed body of China whose wounds are oozing the water with blood! To top this lack of continuity Kevin reproaching Heinz his brutal slaughter of China in a heavily (and understandably) hateful way is attacked physically by Heinz who wants to silence his accuser leading to the two men punching each other into the Piranha water (!) where they continue their fight by wrestling in the water (!) trying to drown each other! Having more luck than brains Kevin and Heinz are not attacked by any killerfish who must have disintegrated into thin air or moved on to a smarter movie shot on a higher budget....
At the beginning and end of the river sequence, we see two panoramic shots of the same stretch of river. Not only are the shots supposed to be taking place hours apart, but the position of the boat shows that they're even in reverse chronological order.
The pig that frees Kevin from the stake changes color three times: It starts out white in close-up, then brown in a long shot, then gray as the phony snout biting the rope off, then back to brown again in a long shot.
The shotgun Kevin uses is a nine shot, 10-gauge shotgun (as specified in the DVD commentary). However, in one scene, he fires it over twenty times without reloading.
At one point Kevin kills a native chief and says that to the girls. The same looking native can be seen being hurt in the movie before.
It would take a lot or piranhas to eat that much meat from man's leg to leave just a bone in such a short time.
During the plane crash scene, the plane is obviously a model. It flies sideways and you can see the strings holding it.
A couple of the darts supposedly stuck in Heinz's back fold visibly upward, showing that they're actually just attached to his jacket.
Obvious use of doll substituting for Kevin when he is sent down the waterfall. The fall shown could have easily seriously hurt him and he comes around the corner too quickly.
Kevin chokes a native too fast. It would take longer to choke somebody to death.
When girl is hurt by a dinosaur glove at the ceremony, it's obvious she is not being hurt. Instead, only fake blood is seen pouring down her body.
When Kevin confronts China he hides behind the barrels, but China could easily shoot through them and kill him.
During the sacrifice to the dinosaur scene, the drummer's beat does not match up with what we hear.