Revealing: In one shot when the boat is pulling away from the waterfall, you can clearly see that the shot is the same one they used earlier in the movie. The water from the waterfall now is going up the cliff! They have just put it in reverse.

Revealing: When the girl is strangled in the boat, after she is dead you can see her abdomen moving as she breathes.

Factual error: During the FIRST battle with an Anaconda, the 55-gallon fuel drums lashed to the deck of the riverboat are swept over the side, where they sink to the bottom of the river. This plot device drives the rest of the movie, since the boat must make a dangerous detour through "Anaconda country." There is just one small problem with this: Fuel drums full of diesel fuel OR gasoline FLOAT on water! The fuel in them makes them buoyant. It would have been a simple matter for someone to get a rope or a boathook and retrieve the fuel drums before they floated away.

Visible crew/equipment: When Jennifer Lopez is in the cabin with John Voight and the snake breaks through the window, if you look closely, you can see the wire that is keeping the face up.