There are two clues to the fate of Will Rodman (James Franco) after the events of Rise of the Planet of the Apes (2011). When Caesar returns to his house, a sign can be seen with an "X" on the stoop by the door. Usually this means someone living there is infected, so it can be assumed he was one of the first to die in the plague. Also, Will's 1980s-era Jeep Wagoneer is still parked in front of the house, covered in vines and vegetation, but it can clearly be seen when Caesar and friends first arrive to the house. Of course, if Will had left his house, he most likely would have driven his vehicle.
The orangutan that is featured prominently in the film is named Maurice. This is a reference to Maurice Evans, who portrayed the orangutan Dr. Zaius in Planet of the Apes (1968) and Beneath the Planet of the Apes (1970).
According to Director Matt Reeves, the original draft of the screenplay, which was written before he was hired, was set further in the future, with the apes having obtained the ability to speak almost flawlessly, and Caesar playing a much smaller role. Reeves thought it would be more interesting to explore Caesar's story at an earlier stage, and asked for permission to re-write the script from scratch. His request was granted, on the condition that he deliver the film in time for the scheduled release date.
The film takes place in 2026.