You'll be fine.
The rumour is that only 1 in 10 (approx) applications even get looked at; the rest are automatically accepted. And even if yours did get checked; IMMI are making next to nothing for the Visa, so they won't be wasting resources looking into bank transactions, etc.
As long as you have proof you were actually on the farm (pictures, pay slips, etc), there's no dramas.