While in the US government bunker, the apes come upon a doll that goes "Mama" in the same voice the doll that Taylor found in the 1968 film which increases the realization that humans once were the dominant species of Earth.
Kingdom of the Planet of the Apes is set 300 years after War for the Planet of the Apes in the Southern California area. Raka's residence is set underneath the ruins of LAX. The clan of Noa reside somewhere within the Los Angeles basin. Proxima Caesar's clan reside near the remains of the Coronado Bay Bridge near San Diego, CA. The observatory is heavily implied to be the Griffith Observatory, based in the Hollywood Hills. This is a nod to the original film saga as the Los Angeles basin is the setting for Escape from the Planet of the Apes, Conquest of the Planet of the Apes, and Battle for the Planet of the Apes. The first films in the "Caesar trilogy" were also set in and around San Francisco and the nearby Muir Woods National Park.
Director Wes Ball explained that he was initially worried about joining the franchise, believing that a direct sequel to War for the Planet of the Apes was "unnecessary" and "unimaginative" since "it would be unfairly sort of compared to that perfect trilogy that came previously in the last 10 years." Once the director landed on the idea of jumping ahead in the timeline that's when he became more comfortable with the idea of helming the next installment. He explained "so, we came up with this idea to stay in the same universe. We're still a part of Caesar's world, but we're cutting many, many years later, after the fact, where you get to really explore what's become of Caesar, what's become of his legacy, his ideas." Ball also shared that the film essentially acts as both a sequel and a prequel, bridging the gap between the previous trilogy and the original 1968 movie. Ball explained: "we find ourselves sort of in the middle, honoring where we came from with this great reboot that happened with the Caesar trilogy, and start making our way to that '68 version where apes are talking and have democracy and all this crazy stuff. So, that was kind of the approach that we took."