BadBiology: The anaconda is depicted as agile and swift when attacking a person from the top of a waterfall. In reality, anacondas are slow-moving creatures, particularly when out of water. Thus, it is impossible for the anaconda to lunge at and capture someone from the top of a waterfall. If it had attempted this stunt it would most likely fallen off the waterfall altogether.

Notice that the anaconda in the movie immediately wraps itself around its victims. This is not an accurate portrayal of the snake. The anaconda is a constrictor, meaning that it must first get a firm hold on its prey before it can wrap itself around it and constrict. Typically, snakes accomplish this by latching on with their mouths and then wrapping themselves around the prey item.