Notoriously, Charlton Heston only agreed to make the film if his character was killed off, so the solution was. Setting aside the actual movie itself, that's an impressive feat no matter how you slice it.
The result: 'Beneath the Planet of the Apes,' the 1970 sequel that bends over backwards to retread the same basic beats of the first film and somehow manages to be even weirder, even more cheaply-made, and conclude on an even darker note than the original. The shocking twist ending of 'Planet of the Apes' doesn't necessarily lend itself to four sequels (let alone even just one), but boy did 20th Century Fox try their hardest to make it happen anyway.
