The rattlesnake could "see" the predator whilst invisible as a rattlesnake has pits on its head that allow the snake to sense heat and track prey through its thermal radiation signature, much like the Predator.
Though still advanced, the technology used by the Feral Predator is much simpler than previous films e.g. the camouflage sections are larger, less armor, and the HUD is very streamlined and simplistic.
During an interview with SlashFilm, director Dan Trachtenberg mentioned the film's creative team struggled with what he called the "À la poursuite d'Octobre Rouge (1990) thing," where the characters speak Russian before transitioning into English. He said they never quite came up with a way to make that work, so instead, the film was shot in English and Comanche. "Both languages are spoken, but when you hear English, it's as if it's Comanche," he said. "But what Jhane is speaking to is on Hulu, there will be a Comanche dub of the movie, so you can watch the entire movie in Comanche with the original actors returning to perform their roles. In an interview with Empire, Trachtenberg went on to say "There's a lip-match (choosing words to match the actor's mouth movements as closely as possible) that we do now. It won't be like watching old kung fu movies."
Sarii, Naru's dog and constant companion, had no previous movie experience, and was adopted specifically for the movie only 2 months before shooting. Sarii's real name is Coco, and she is a Carolina Dog, a rare breed of wild dog that followed the first humans to cross the Bering Strait 4,500 years ago. Trachtenberg wanted to cast a dog that would be period-accurate, and Carolina Dogs are direct descendants of those dogs. Amber Midthunder (Naru) called Coco "a little bit of a hot mess - but in a sweet way" and said that "obviously it all ended up fine, because she was great, and everybody loves her."