Question: Since World War 3 was the cause of the nuclear devastation, as evidenced in Beneath the Planet of the Apes, how is it that Dr. Zaius doesn't know the full story of the rise of the apes over the humans? Wouldn't the story be passed down?
Chosen answer: Dr. Zaius did know the true history of man and ape, but he deliberately hid the truth from the other apes. For Zaius (and other high-ranking apes who were guarding the secret), it would be shameful and demoralizing to ever admit that humans were far superior to apes in the past and that they could, potentially, conquer the apes. In more than one scene (such as the paper airplane scene in the first film), we see Zaius obviously frustrated that Taylor's very existence threatens to expose the truth.
Question: The apes don't seem to have developed industrially; they are using horses and riding in carts. So are those rifles and bullets 2,000 years old?
Answer: SPOILER ALERT: They didn't develop along the same timeline as humans; they developed in a post-human world, with technology sitting around waiting for them to pick up. As Dr. Zaius reveals at the end, they knew of humankind and how human civilization collapsed, so they likely made a conscious decision NOT to develop industry, at least not on the scale we did, for fear of destroying the planet/each other all over again. They could pick and choose which human inventions they adapted, such as basic firearms like rifles, and continue manufacturing these on a small scale, while largely maintaining a pre-Industrial Age civilization.
So bullets and rifles, but not cars? I didn't notice any electric lights, either.
Have you never seen a Western? Guns were developed well before cars and electric lights.
Answer: According the Apes' history, the earth was destroyed in a nuclear war, which causes an Electro Magnetic Pulse. It causes everything electronic to shut down. The apes were smart, but they were not scientists or engineers to work out the complex inner workings of a vehicle.
Question: What makes Taylor think they're on a planet in the constellation of Orion some 320 light years from Earth? How did he come to this conclusion?
Chosen answer: Because that's where the ship was originally headed. Some sort of malfunction made it turn around and return to Earth.
Question: Why do the humans in "Planet Of The Apes" all wear clothes? I am fully aware that the film was made in 1968, for a general release, permitting it to be shown in cinemas or on television, and 20th Century Fox would never have been allowed to make a movie in which humans all ran around naked. But, since the film is supposed to be set in a post-apocalyptic world, where humans have regressed back to being wild creatures, without language, lacking the skills to make or create anything, where do they get their clothes from? (And their clothes fit, too.) Did anybody ever come up with an answer to this, apart from the obvious reply that they wanted to get the film past the censor?
Answer: Unlike other primates, humans walk upright which exposes their genitals. They would instinctively cover them for protection. Humans also have very little body hair, so would cover themselves against the elements. Finally (spoiler alert) as these humans devolved from actual humans, it's likely something they did because their ancestors did it and it's been continued through the generations.
Answer: The humans have become mute, but not regressed to being "wild animals." The apes are the superior species but humans still have a high-level of intelligence, live in a complex, interactive social group, communicate non-verbally, and would have the ability to make simple tools and protective clothing. At the very least they would be equal to Neanderthals, but seem more advanced. The real answer is, of course, it's a 1968 movie when there were more stringent rules regarding nudity in films. If there was any, it likely would have been "X" rated, therefore limiting its audience and in which theaters it could have been shown in.
Question: Was Doctor Zaius really aware of what happened to the human race? Many times during the film, he does things that indicate such a possibility, like crushing the paper airplane.
Question: World War 3 may have been the reason for the nuclear war, but what caused World War 3?
Chosen answer: It's never stated what caused it (in this movie, at least). So much time has passed that historical records have been lost or destroyed, and the remaining humans are no longer literate, nor do they have any inkling about their species' past. The apes also do not appear to know the reason, only that mankind somehow destroyed their own civilization.
Question: What caused the original nuclear devastation depicted in the movie?
Answer: I think that this is meant to be a mystery. Taylor/Charlton Heston, an astronaut, leaves a world set somewhat in the future after 1968 (when the movie was made) but still recognisable to cinema-goers at the time, to travel through a "time vortex" to arrive in a world in a distant future, which has changed beyond recognition. Taylor meets the orangutan Zaius/Maurice Evans, and Zaius hints that he has some idea of what had happened, but Zaius' knowledge is either limited, or else Zaius is not going to tell Taylor (or his fellow apes) the full story. At the end of the movie Taylor discovers that, at some point between his leaving his own time and arriving in the "Planet Of The Apes", the world had been devastated by a nuclear war, but I think that the exact time, causes of, and course of this nuclear war are deliberately left as a mystery. Sometimes I think a bit of unresolved mystery actually improves a story, and I think this is the case here.
Chosen answer: World War III.
Question: Why does it take Taylor so long for him to figure out he's really still on Earth? Shouldn't the fact that the apes all speak perfect English be a dead giveaway?
Answer: This is an issue with the "Planet of the Apes" films. The astronauts never question why the apes speak English, why all animals (like horses) are identical to ones on Earth, the vegetation is the same, the star constellations have not changed, etc. You really just have to attribute it to a "suspension of disbelief" where we are expected to accept the premise that the main character does not work out the truth until the big "reveal" at the end of the film.
Answer: At the time, it was a standard film convention to have the characters speak the language of the country that produces the film. Sure, they could all speak "ape", but that would have been an added layer of complexity (and pre-production) that just wasn't done in Hollywood at that time. Even most WWII films had the Germans, French, etc, all speak English. But to give an in-film explanation: he's on a planet where apes evolved from humans just like him, so maybe he just assumed that English had evolved there, as well. In a universe as vast as ours, it's actually a statistical certainty that English has independently arisen on another planet.
Answer: He's in the same location as Ellis Island. Thousands of years have resulted in significant changes geographically.