This is Oliver Stone's first film in nearly 17 years to be photographed with Panavision anamorphic lenses. After Nixon (1995), his 2.35:1 films were cropped to that ratio via shooting in Super 35. He was convinced to return to anamorphic by cinematographer Daniel Mindel, who has shot all of his features except Domino (2005) in the format. Mindel told Stone during their first meeting that if the plan was to shoot in Super 35 or digitally, then he wasn't the right man for the job.
The trivia item below may give away important plot points.
The "fantasy" ending is the literal ending of the book, in which there is no indication that it was a fantasy. The line "live like Savages, beautiful Savages" is accordingly in the novel the last thoughts of Chon as he lies dying.