A single spelling error can cost you your job! (A major blunder, where the name of the country was spelled wrong on a coin.)
http://news.bbc.co.uk/2/hi/americas/8511910.stm
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)