Everybody makes mistakes. Sometimes things work out for the best.
With bank errors, things usually go bad. If money goes missing you'll bounce checks and be unable to buy things you need.
What if there's a bank error in your favor? It's not much better. Sometimes unexplained deposits - large ones - may show up in your account. If the money isn't yours, don't spend it.
A Florida man allegedly took advantage of a $90,000 bank error recently, only to end up in jail [via DepositAccounts]. Somebody fat-fingered his deposit, adding a few zeroes to a $900 transaction. Not surprisingly, they eventually noticed the mistake.
It also happened a few weeks ago in Alaska after $230,000 popped up out of thin air. However, occasionally somebody gets away with it. Last year a New Zealand couple made off with a few million after a bank error and have not been heard from since.