Oh dear, I love it when someone is stupid enough to argue out of pure ignorance:
http://en.wikipedia.org/wiki/Ton
The object of the sentence are the MISTAKES, the ton is simply quatifying them.
Would you say "There is a 100 mistakes" or would you say "There are 100 mistakes"? Don't bother answering because you'll be wrong.
And the plural of Ton can be tons (see link).
Belfast education... oh dear: "There'd be a ton of mistakes, that there'd be."
If he has a Belfast education, how come you are doing an impression of a Cornishman pirate?
