Due to the fact that many of the native South American actors wear very little and many of their women appear topless in the picture, reportedly, filming each day started with the non-South American cast and crew personnel performing naked aerobic exercising.
The film was "released with native language dialogue" and "became the first feature ever made for U.S. markets in a principal language other than English" according to the book "Picture This!: A Guide to Over 300 Environmentally, Socially, and Politically Relevant Films and Videos" (1992) by Sky Hiatt.
According to director John Boorman's book "Money Into Light - The Emerald Forest: A Diary" (1985), Boorman's initial choice for the part of the son Tomme was C. Thomas Howell. When Howell was unavailable, John decided to use his own son Charley Boorman for the part.
According to TV Guide, "In October 1972 an account written by Leonard Greenwood appeared in the Los Angeles Times. It told of a Peruvian engineer whose son had been kidnapped by a band of Indians and of the man's successful search to locate the child. Screenwriter Rospo Pallenberg saw the news item and took it to producer-director John Boorman". The result was this movie.
Star Powers Boothe almost drowned during the shooting of one sequence where Charley Boorman was assisting Boothe cross a river. Boorman's pleas for assistance were initially interpreted by distant crew personnel as being part of his performance.
Charley Boorman broke the same toe four times during production. After the lengthy shoot, during which he had spent virtually the entire time barefoot, his party trick was to light a match on his bare feet.
The names of the indigenous South American tribes were "The Fierce People" and "The Invisible People." There is a reference to a former tribe named "The Bat People." The members of "The Invisible Tribe" refer to the dam builders as "The Termite People."
According to the book "Picture This!: A Guide to Over 300 Environmentally, Socially, and Politically Relevant Films and Videos" (1992) by Sky Hiatt, "John Boorman lugged a production crew and truckloads of equipment where no equipment had gone before to film on location in the Amazon basin".
The climate during the filming of the picture was regularly hot, humid, rainy and uncomfortable. Director John Boorman has said that the wet inclement weather in Belém in Pará, Brazil was "a daily torrential downpour".
Many movie posters for the film featured a long blurb that read: "What kind of man would return year after year for ten years to rescue a missing boy from the most savage jungle in the world? His father. The Emerald Forest (1985). Based on a true story."
This movie was first released in the same year that John Boorman directed the television short Journey Into Light (1985) which had a very similar title to Boorman's book "Money Into Light: The Emerald Forest: A Diary" (1985) which was about the making of this picture.