Other mistake: There are two mistakes when Grey is at the computer trying to figure out why her patient is having seizures. The camera pans out showing Bailey walking up - if you look at the computer it shows a login screen, but when Grey shows Bailey the screen it changes. Next one is when Grey blows up the pic of the taratoma - when they leave the picture on the computer it's actually a brain.
The Lion Sleeps Tonight - S8-E18
Other mistake: At the beginning of the episode, when Meredith, Derek and Zola see the lion crossing the street in front of the car, the lion roars and it is clear that the lion is not missing any teeth. However, later in the episode, Richard removes a tooth that had gotten lodged in the male mauling victim's arm. The victim was the lion's owner and the attack happened in his house, so by the time the lion was out the tooth should already be missing.
