Nick Offerman can be heard narrating the documentary on Machu Pichu in the beginning of the film. One of the several ties to Aubrey Plaza's role in the series Parks and Recreation (2009).
The photograph of Beth (Aubrey Plaza) that Zach (Dane DeHaan) grabs near the end of the film was clearly taken from the final scene of the Parks and Recreation (2009-2015) season 4 episode 6 "End of the World".
Near the end, Beth (Aubrey Plaza) is talking on the phone with "Andy." This is an obvious reference to her role in Parks and Recreation (2009) in which her husband, played by Chris Pratt, is called Andy.
One of three films Aubrey Plaza and Anna Kendrick appear in together, along with Scott Pilgrim vs. the World (2010) and Mike and Dave Need Wedding Dates (2016).