There was so much in this episode I do not even know where to begin. So let me try to break it down for you.
Lizzie creeps me out (she reminds me of Billy from the comics). This episode made her more mysterious than ever before. She was trying to help out with the walkers, but as soon as she tripped, she stayed on the floor crying. Hershel had to come and save her. The thing is, when she had the walkers attention, she had a look in her eye that made it seem like she was going to kill the walker. I think later on in the season she is going to do something that is going to surprise us all.