In 2006, the Chicago Tribune found several errors on then-current Chicago Transit Authority maps intended to help riders navigate their sometimes-confusing "L" and subway lines.
The spelling errors and missing stops certainly didn't clear up that confusion.
Predictably, then-president of the CTA, Frank Kruesi, fired the person he deemed responsible -- even though it's doubtful a single person designed, wrote, and proofread the map. Clearly, this was more of a group effort.
Repairing the errors required an expensive (but necessary) $75,000 fix, leading one commenter at the above link to rightly wonder how much the CTA would have saved by hiring a part-time proofreader.