 Even though Charlton Heston (Taylor) is not listed in the full  cast/crew; he does appear in archive footage lifted from the  conclusion of "Planet of the Apes" where he kisses Zira goodbye.  That (color tinted) scene appears during Ziras interrogation, by  government officials, while under the effects of sodium pentothal (a  truth drug) that puts her in a dream state; thus resurrecting  several brief glimpses of scenes taken from "Planet of the Apes" and  "Beneath...".