- Very Loosely Based on a True Story: Some (including Harlan Ellison) would argue, to the point of Based on a Great Big Lie: The novelization had a postscript revealing that the child in the real incident was the son of a Peruvian laborer, a lumberman working near the Javari Mirim River; not an American engineer. John Boorman claimed he had read the story in "the Times". Then Judy Herman of the Southern California Answer Network (a pre-Internet research service) revealed the following:
- Rospo Pallenberg, not John Boorman, found the original true story: Los Angeles Times, October 8, 1972, sec. F, p. 10. He created the fictional story and presented it to Boorman, who sold it to Embassy Pictures as being based on something he had read.
- Boorman claimed to have talked to anthropologists who studied the Mayoruna, the tribe from the real incident, saying the son was still living with them. However, anthropological journals regularly report in considerable detail on the Mayoruna, and have never mentioned an adopted outsider.
YMMV / The Emerald Forest