When Eli Roth and his crew approached villagers to be extras in the film, he soon realized that they had never seen a movie and had no concept of what one was. To demonstrate what a movie was, Eli brought a TV and a copy of Cannibal Holocaust (1980) and had a screening for everyone. The villagers loved it and thought it was a comedy. They gladly acted in the film.
Eli Roth disclosed that the tribe offered a two-year-old child to the production designer as a "thank you" for including them in the film. The production designer politely declined the offer.
Eli Roth would only audition actors who agreed to be vaccinated for yellow fever and to film deep in the Amazonian jungle with no bathrooms, surrounded by tarantulas, snakes and poisonous frogs that could kill you on contact. After filming was completed, the cast and crew were treated for parasites.
Out of all the villagers who signed up to be in the film some of them ended up working as crew as well.
Eli Roth said that the film released to theaters is the original film he created. The MPAA did not request any scenes be cut in order to obtain an R-rating.