Not that this is necessarily an Illustrator error, but it's the kind of thing I've done plenty of times while using Illustrator and FreeHand. You grab what you think are all the pieces of something and move them. And then you realize you didn't grab all the pieces. Sometimes you don't notice until the piece is printed. That is a bad feeling.
This error -- on the side of a beverage cup -- was made in 2001, according to the copyright notice. I've been to every Fair between then and now and this is the first time I've noticed it.
Unrelated note: The Minnesota State Fair has been trying out a new logo in the last couple years. More of a retro logo. I like it.