When Sachi started humming "Rudolph the Red-Nosed Reindeer".  Okay, the scene was supposed to be emotional, but humming a Christmas song about a reindeer being ostracized for having a glowing red nose, just made me want to laugh more than cry at that moment.

Also, the from the moment she appeared and started talking about how much she didn't want to die, and how she wanted to go home, I knew she was going to die at the end of that episode.  It just seemed so predictable :/