Stupid retconning in this film

Well, they had written themselves into a corner with the last movie. Charlton Heston said that he would only star in it if the world gets blown up in the end.

But fear not, here comes a screenplay that just ignores many things in the first to give us a mostly stupid fish out of water cheese fest (though admittedly, the ending is really dark).

So, in the first movie it is established that the Apes think flying is impossible. They are even astonished when Taylor forms a plane out of paper. Also, there is no higher technology on display, the apes don't even seem to have discovered electricity.

Yet, we are to believe that while Zaius and the Gorilla army are off to fight the mutants Zira, Cornelius and Milo (an ape we have never heard off before, who is conveniently a "genius") for some reason travel to the forbidden zone again, even though they where just accused of heresy and an unsanctioned trip to the Forbidden Zone certainly won't help. They also manage to find Taylors ship, recover it from the bottom of a lake, repair it, even though they don't know anything about technology, manage to get the thing into the air and also travel back in time? And why? They weren't aware that there would be a nuclear explosion!

And then there's Cornelius story about how the Apes came to be the dominant species on the planet. Apparently a virus killed all cats and dogs, so people began keeping apes as pets (because a 400 pound Gorilla that could rip you in two or even a dominant chimpanzee that can rip your face off would make for terrific pets). And then over time they learned to speak and a revolution took place.

Except that this is not at all what was established in the first movie. There the apes believed that humans where primitive cattle not capable of higher consciousness. Even the idea that apes evolved from man was preposterous to the apes because they thought humans so primitive.

Also, we are to believe that Zira and Cornelius are supposed to look like regular chimps? In the first movie the apes worked because it was thousands of years and several atomic bombs later. So I took that the apes evolved through the radioactive fallout, their appearance changed, they became more intelligent and developed vocal cords capable of human language (which apes physically cannot do). But as it is presented here, that they could be mistaken for regular apes just doesn't fly at all.