This post, by the way, kind of assumes you saw "Planet Terror", Robert Rodriguez's contribution to the interesting-but-flawed film 'Grindhouse'. And it was, in fact, interesting...but flawed. What was the flaw? (Apart from casting the human particle board known as Rose McGowan in the lead female role, that is.) Simply put, it's the flaw of the script's actions not following its words. Slightly less vaguely put, it's that it's not enough to have characters telling you that a female character is strong, powerful and self-reliant, you actually need to have her being strong, powerful and self-reliant. Even if the film's text is about female empowerment, it's not going to matter if your subtext is sexist as all hell.
Basically, for those of you who haven't seen the film, it centers (more or less) on Cherry Darling, a go-go dancer who discovers her true calling in the middle of a zombie outbreak caused by a theft of biological weapons gone wrong. She becomes a rough, tough zombie-killing cyborg with a machine gun for a leg (replacing the limb that was torn off by zombies, natch) who leads the human resistance to safety. Sounds nice and feminist, right?
Except for one thing. El Wray. El Wray (played by Freddy Rodriguez, no relation to the director) is Cherry's ex-boyfriend, who makes a point of telling her how strong she is, how tough she is, how powerful and resilient and charismatic and heroic she is...um, while he's, um, actually doing all the heroic stuff. He rescues her from the hospital, he literally forces her to stand on her foot and prosthetic leg while she's sitting there moping, he rescues her another two or three times, he finds her the machine-gun leg, and her heroic plan for guiding the refugees to safety? It's his plan. She follows it after he tells her, with his dying breath, to become their heroic leader.
Seriously, that's the end of the movie. "Become a charismatic and heroic leader, Cherry." "Yes, sir." There's just no way to make that scene work, because it undercuts itself.
And this is the difference between feminism as text and feminism as subtext. Lots of horror movies have a text that isn't particularly feminist--they have psycho killers with mommy issues galore, axe-wielding maniacs, and guys who love to kill women for fun. But when the female characters respond by fighting back and killing the killers, that shows them, through their actions, to be strong and resilient and powerful. Whereas if they aren't actually strong, resilient, powerful people, just having someone else in the film talk about how great they are isn't going to ring true. That's why "Planet Terror" doesn't work. It doesn't ring true.
(That, and it's not nearly as cool as the trailers that follow it. Why are those not on the DVD, dammit?)