It's not too widely known that Forrest Gump was based on a novel. Released in 1986, Forrest Gump by Winston Groom is about an "idiot savant" named Forrest who goes wherever the wind takes him. Despite his low IQ, he possesses incredible mathematical skills and is capable of doing almost anything he wants, even if he has no idea what that is. The novel consists of him going on wacky adventures where he is occasionally joined by childhood sweetheart Jenny Curran who, like in the film, appears and disappears throughout the novel.
The film adaptation of Forrest Gump softened some of the novel's rough edges and decided to make Forrest into a much more innocent character. But the greatest improvement actually comes from the omission of certain events. For the most part, the film accordantly adapts Forrest's adventures that appear in the novel, including college football, a ping-pong championship, the Vietnam war and starting up a shrimping company named Bubba Gump; however, there's also a lot more that never made it on screen, and his most absurd exploit was completely omitted — he becomes a temporary astronaut who goes into space with an orangutan named Sue.
In the novel, Forrest wanders into an anti-war protest, but instead of merely reuniting with Jenny and then going home as he does in the film, Forrest is taken into custody at a psychiatric hospital. While there, they find him to be a mathematical genius. NASA gets word of his skills and they offer to send him on an experimental space mission where he will become the ship's backup computer if the real computer fails. It's here where the cannibals actually come in because the ship crashes onto an island in Papua New Guinea where Forrest and his fellow astronauts are held captive by a tribe of cannibals for four years.
Upon joining the space program, Forrest meets Major Janet Fritch, the first woman to ever go into space, and Sue, an orangutan who is an experienced space explorer. As they're about to launch, Forrest realizes that Sue has somehow been replaced by a different ape. No one takes this change as seriously and they take off anyway. Things quickly fall apart when Major Fritch is struck in the face by a glob of orangutan pee unbounded by the lack of gravity and non-Sue decides to throw a tantrum. He rips up the wires from the control panel and the ship crashes in Papua New Guinea.
In hindsight, removing this from the movie seems like the wisest decision the filmmakers could have made. Not only would it have been an out of place, screwball comedy bit in an otherwise heartfelt drama, but once they get to the island, things are kind of overshadowed by the racist stereotypes that would have definitely stained the film's legacy.