War for the Planet of the Apes has a big connection with the first two original Apes movies.
Throughout the first trailer for War for the Planet of the Apes, a young child can be spotted with the gorilla Maurice. She’s in the beginning of the trailer, hugging Maurice tightly and riding a horse while Caesar is staring at her. According to Entertainment Weekly, this young girl is Nova, the same mute character played by Linda Harrison in the original Planet of the Apes and Beneath the Planet of the Apes.
While speaking to EW, director Matt Reeves revealed that Caesar finds Nova while trying to hunt down Woody Harrelson’s character, Colonel. Reeves wanted to include Nova in the film to highlight that there’s a battle “not just between the humans and the apes, but in Caesar’s soul.”