“Your appendix is a vestigial organ with no known function but it will kill you if it goes awry.” That’s the clever moral Professor Childress of Legal Profession Blog draws from the story of the attorney who inadvertently submitted an appendix that included his margin notes commenting on the court’s prior opinion. His post also has additional links regarding the story.
Of course, your appendix on appeal does have a function (though I can understand how the temptation to write that line was irresistible to Professor Childress). But the larger point remains: proof your appendix as carefully as you do your brief.