Ayup. A boy I went to theater school with got hit by a car when he was about 11. The nurse had been on the clock for like 12 hours already, and she read the request for 4.5 cc of morphine as 45 cc. 

Luckily, the mistake was caught right away, so instead of dying, the kid just spent 6 months in a coma and the year after waking up in a wheelchair. He never could sing after that, either.