In the episode where Crusty's daughter Sophie tracks him down at the Book Festival, there is a mistake with her violin case. When Crusty goes back to his car to get Sophie's violin to bet in his poker match with Fat Tony, Sophies name is clearly colored onto the case in big, colorful letters. Later, when Homer and Crusty go back to Fat Tony's mansion to retrieve the violin, they have to take all of the violin cases that are filled with guns to find the right one. They could have easily found it by looking at which case said Sophie's name on it. But the slipup is, that there was no name on any of the cases. Later, when Crusty shows up by Sophie's window with the case, there is clearly no name on it. The animation crew clearly left out the name. This mistake could have easily been avoided.