This should be a fun topic. Songs that you are aware of, in which at least one mistake was made, but for whatever reason, they chose to leave it in.
Example: In "You're Only Human (Second Wind)" by Billy Joel, there is a line in there (near the end) in which he sings, "ssssssssssssometimes that's what it takes." He wanted to go back in there and correct that, but since it was a song about not being perfect, Columbia suggested that he leave it that way. And so it was.
I'm sure that there are others, but that is one of the few that I know of in which a mistake was left in.
Example: In "You're Only Human (Second Wind)" by Billy Joel, there is a line in there (near the end) in which he sings, "ssssssssssssometimes that's what it takes." He wanted to go back in there and correct that, but since it was a song about not being perfect, Columbia suggested that he leave it that way. And so it was.
I'm sure that there are others, but that is one of the few that I know of in which a mistake was left in.