The only film in the original series of five that does not star Roddy McDowall, who was committed to another project, his sole directorial effort "Tam Lin". Archive footage of McDowall as Cornelius is played at the start, and David Watson plays the character in the film proper. Despite this, McDowall is often pictured on video and DVD packaging for this film. Interestingly, Watson and McDowall appeared together two years earlier in the made-for-television musical "The Legend of Robin Hood" with Watson in the role of Robin Hood and McDowall playing Prince John.
Due to the smaller budget of this film, the vast majority of the extras cast as apes (including the ones sitting close to Zira and Cornelius) wore pullover masks instead of the famous ape make up.
James Franciscus, who had spent most of his career playing doctors and lawyers, so welcomed the opportunity to wear a costume that could best be described as minimal. Franciscus was a natural athlete and keen tennis player, so was in great shape for the shoot.
According to writer Paul Dehn, the idea for the film came about because of the iconic imagery of the first film's climax.
It took a lot of persuasion for both Charlton Heston and Kim Hunter to reprise their roles for this film; Heston didn't believe in making sequels, as a rule, and Hunter had such an ordeal with the rigors of dealing with the makeup appliance during the first film.