Question about the ending...(spoilers)

I pretty much got all the twists at the end, but the only thing I don't understand is how Alice (Jennifer Grey) was able to use her free will to blow the dust in Caro's face instead of JB's. Caro said she could control Alice because she infected her with the cat virus on the infected swab, but then she's obviously not since Alice screws her over in the end.

Just before Alice blows the zombie dust it shows her clutching her leg as if this is supposed to be some telling detail but I didn't get it. Did Alice work up a cure for her and Wesley like she said she would? It didn't show it happen and never even mentioned it again so I was unsure. I liked this movie but it was edited bad, and left a lot of plot holes. If she did create the cure, wouldn't she have told Caro about it and given it to her too? Remember, Alice liked Caro and thought she was infected too, and didn't know she was behind it all until she was already at the zombie ritual site. So if Alice told her about it then Caro would know she was no longer under her control. Plus it made it look like Wesley was in some sort of trance state when the last we saw of him he had been taken by the superintendent's goons, which was after Alice said she could make the cure so if she did then he wouldn't be in a trance til his brother blew the zombie dust in his face. Confusing.

Maybe I'm over-analyzing it and it just doesn't make sense as written. Or maybe it made sense as written and filmed but they gutted the crap out of it in editing room. Alice said they'd have to infect an animal and extract the antibodies to make the cure - it didn't show any of that. There were visual references to a cat creature, which seemed to tie in with the whole cat disease thing, but that turned out to be nothing. Caro really seemed to like Wesley, and grew up with the brothers, yet suddenly she's taking her revenge out on both like, 25 years later instead of their father who was the one who actually killed her mother and denied her the legitimacy and inheritance she wanted. What, did she learn voodoo yesterday? Why now?And why did the evil brother tell her as he was dying that he was going to give her a lot of money when all was said and done, as if he knew she was the voodoo priestess all along? Maybe it was just me, but he had a definite look of surprise on his face when she unmasked, implying he had no idea it was her - and he clearly didn't know she was his half-sister.

There were a lot of really awkward and abrupt jumps between scenes and discrepancies like I mentioned above were rampant. With a few tweaks this could have been much better.