Primatologists who saw the film said the apes' behavior was surprisingly realistic. Karin Konoval's performance as Maurice the orangutan was especially noteworthy.
A shot of Bad Ape from behind, in a big, hooded winter coat, is the only time Steve Zahn appears onscreen without motion-capture gear.
While promoting Dawn of the Planet of the Apes (2014), Andy Serkis was asked if the ALZ-113 drug had also affected apes outside of Caesar's tribe. Matt Reeves and Mark Bomback took note of it, which led to the introduction of "Bad Ape" in this film.
Matt Reeves pointed out that the apes in Rise of the Planet of the Apes (2011) and Dawn of the Planet of the Apes (2014) don't wear clothing. The ape society seen in Planet of the Apes (1968) wears clothing, and Bad Ape is also supposed to be the start of a progression in this direction. To survive in a harsh winter, he wears heavy winter coats he scavenged. This is primarily necessitated by the fact that he is bald, similarly to Rocket. However, while Rocket likely has Alopecia, Bad Ape seems to have lost his hair from old age.
According to Matt Reeves, the name of the group of rebelling humans are the Alpha and Omega, a reference to the bomb the mutants worshiped in Beneath the Planet of the Apes (1970). The logo on their helmets and flag matches the original logo on the bomb.