It was a horror/monster movie (or, with slim possibility, a TV show, but I'm fairly certain it was a movie). It was about little monsters or aliens (unsure) that attacked people and ate them. I believe they were essentially elongated heads with lots of teeth, about the size and shape of a football. I don't remember how or why they showed up, or even how they were ultimately defeated. I'm pretty sure it was live-action.
The one thing I do remember distinctly is that, at the end of the movie, as the camera pans up after the ordeal has been settled and everyone thinks its over, a mountain in the distance stands up and opens its mouth, revealing itself to be a massive version of the smaller creatures. That's the only distinct piece I have to go on.
The exact details from the middle, I'm not sure. But the "mountain is actually a monster/alien" ending is the firm detail in my mind. I was very young, so it's all I remember clearly.
I saw it at home in the late 80s or early 90s in the United States, but I don't know how new it was at that time. It was color, and I don't know if it was a rented movie on VHS or shown on TV, but I would guess it was on TV.
I'm fairly certain it is not the movie(s) "Critters" about the little hairball monsters, although if I'm wrong (and that ending shows up in one of those films), that's okay.