The most jarring one I can recall was in a Big Five published book where the name of one character was swapped for another character's. It was jarring because, in that scene, the mistakenly identified character wasn't even in the room, but is given a piece of dialogue that logically belongs to a different person. It was just such a weird mistake that I had to wonder how it happened. Word typo? The author miswrote it? Editor messed it up? Who knows...