The ape makeup looked great, but it was cumbersome on the actors. For one, it limited their ability to eat. According to Kim Hunter (who played Zira) and Roddy McDowall (who played Cornelius), they had to eat in front of mirrors to avoid damaging their make-up. It was vital they did not disturb the makeup since it took 3 and a half hours to apply. As McDowall documented, the ape actors would take their breaks and lounge around on set while still in full make-up.
Since the ape actors would be in make-up all day, it would be easy to snap photographs of them. That meant security had to be extra strict. Army Archerd of Variety spoke with producer Arthur P. Jacobs, who explained the need for secrecy. Archerd summed up the situation as:
“The unusual ape makeup [is] worn by most of the 235 actors in [the] pic. The studio is not permitting any stills to be published until pic’s release next Easter and is also guarding sketches and photographs of the simian city, which the art department created over two years.”