Whenever there is a movie that use America Indians and their languages, they sound very slow and choppy. Did these languages actually sound like that or are they just trying to work with whatever we have left of from those languages, or are they just the best guesses we can come up with?
A lot is going to depend on what movie you're talking about. That is, if the movie is written by, directed by, and stars American Indians, the language is likely to be accurate. If the film credits include a thank you note to members of a tribal nation, it's likely accurate. WONDER WOMAN, for example, had both a Native actor in the role of Chief, and a language expert on set to help with pronunciation.
However, if everyone associated with the movie is non-Native, odds are they made up something or did what they thought indigenous speakers sound like.
You may find the documentary Reel Injun or the book Celluloid Indians interesting.