I've got more to say about Frozen, and this time, I'm talking about the villain. Highlight the text to read it.
At what point does Hans turn evil? Either he was evil all along, and just pretending to be good, or he was good and later decided to turn evil.
The biggest problem with Hans being evil is that he saves Elsa's life in the ice castle, two scenes before he reveals his evilness. If his plan was to kill Elsa all along, it makes no sense for him to save her life. Granted, he only had a split-second to think things over, but it's strange that his instinct is to save her from the Wesselton Sniper.
Also if he's evil all along, it makes little sense for him to go on the expedition to save Anna / confront Elsa. From his standpoint, the best case scenario is one in which both princesses die. Granted, he wants to make it seem like he's deeply concerned for their safety, but he could have done that without risking his life.
You could argue that he goes out because he wants to be 100% certain that they're dead, but...well...he doesn't do that when Anna is dying. He just gets up and leaves, instead of making sure she's dead. Maybe he just got lazy and tired of waiting in between those scenes.
Another (minor) problem with Hans being evil is that everyone magically knows about it. The foreign dignitaries all cheer when Hans is punched, even though no one told them Hans was evil. Kristoff also makes a move to attack Hans, even though he has never seen Hans before and doesn't know he's evil. Maybe everyone just guessed that Hans would become a villain?