Errors

There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors.
Can you find the three errors in this sentenceeee?
Contrary to belief, Wikipedia actually has less factual errors than traditional printed encyclopedias.

Source: Wikipedia
A man is smoking and leaving smoke rings into the air.
A woman gets irritated with the smoke and says to her lover: "Can't you see the warning written on the cigarettes packet, smoking is injurious to health!"
The boy replies back: "Darling, I am a programmer. We don't worry about warnings, we only worry about errors."