The forest scenes were filmed in Purgatory Chasm, a Massachusetts state reservation. Interestingly, while stumbling through the woods, the Ken Watanabe character says to the Matthew McConaughey character, "You are in purgatory".
Aokigahara Forest near Mount Fuji in Japan, otherwise known as the "suicide forest" sees an average of 3 suicides a week. It is also said to be haunted by multiple "Yurei" - Japanese ghosts who are angry at their own deaths. This premise was previously explored in the short film Shawn4Ever (2012).
This was the first film in the 68th edition of the Cannes film festival to be booed by the audience.
Before production, Director of Photography Kasper Tuxen took Matthew McConaughey and Ken Watanabe's stand-ins, Bradley J. Van Dussen and Michael Tow, on location to record test footage. The two recreated essentially the whole film and the footage was shown to Gus Van Sant.
The screenplay for this film was featured in the 2013 Blacklist; a list of the "most liked" unmade scripts of the year.