I was appalled to see the main character destroy a huge alien ship with merely a molotov cocktail, but it's not as ridiculous as I first thought. They actually explained it a bit before it happened: The toxic gas that the alien ship spew out a minute before showed her that it was highly explosive when touching fire. She noticed it and with the molotov cocktail she basically caused that toxic gas inside the ship to explode...
Still, quite an obvious vulnerability that humans with more firepower than her could have used before to defeat them, and a bit stupid for the aliens to carry such a highly volatile gas inside their ship, so it's still quite a bit ridiculous, just not as highly ridiculous as I first thought.
And for her character it played out one of the themes built up in the bunker, when she told the story about her always running away when trouble appears, so her taking action fulfills her character arc, though her taking action against the guy in the bunker did that nearly as well.
That said, I still would prefer a fanedited version, where it ends with her saying "Come on".