Toward the end of the episode when Callie and her father are making their peace outside the hospital, if you look closely, you'll notice Callie is wearing two totally different earrings. See more
Dr. Meredith Grey
When you get sick, starts with on single bacteria. Pretty soon, the intruder duplicates... Becomes two. Then those two become four, and those four become eight. Then, before your body knows it... it's under attack. It's an invasion. The question for a doctor is: once the invaders have landed, once they've taken over your body... How the hell do you get rid of them?