I love this bit of small print at the bottom of my hard copy bank starements:

Please ensure that you report in writing any errors or irregularities found within this statement within 30 days of the statement date, If you do not, the statement of account shall be conclusively deemed correct except for any amount credited to the account in error.

Translated, if the bank charges you too much in fees or something and you don't notice it in 30 days, you're screwed. If you get an unexpected deposit in error by the bank, they can revoke the funds any old time they like. What if I already spent it? Too bad, you're screwed.