In NFS cache #307 (at the edge of the controlled burn area you explore on Day 77) is a copy of the book 'The Accidental Savior' by fictional author Terrence L. Greenbriar. This is the father of the protagonist in Fullbright Studios' game Gone Home.
Literary References
While not necessarily concerning references to actual literary works (though Jane Eyre is available in one of the NFS cache boxes), some of the books in Firewatch are references to other franchises.
Metal Gear Solid
One of the books that Henry brings with him from Colorado to read during the summer is 'The Patriots', the shadowy organization behind many of the events in the Metal Gear Solid franchise. The book is written by Donald Anderson, also known as the DARPA Chief from MGS1, and the cover art depicts a star-spangle revolver, clearly referencing the title of MGS4: Guns of the Patriots.
Various Steam Achievements
Complete the indicated task to unlock the achievement.
Achievement
How to unlock
"Back to work."
Completed Day 2
"Burn the place down."
Completed Day 77
"Good first day."
Completed Day 1
"Someone's out here."
Completed Day 76
Bee Plot
Got stung by a bee. It happens.
Firewatch
Completed Day 79
Love Turts
Adopted a turtle as a pet. The average lifespan of a box turtle is fifty years. It will outlive you.
Ol' Shoshone
Listened to the tape of "Ol' Shoshone." Cavorted among the aspens.
Shutter Bug
Filled a disposable camera with photos.
The Life and Times of Raccoon Carter
Got attacked by a raccoon; probably didn't get rabies.
Woodland Critters
In addition to the deer Henry sees while first hiking to Two Forks, there are several encounters with the fauna of the Shoshone that can be experienced during the game.
Gone Home...