Question about bonus phrasing

It does sound like bait and switch.

joe ferris said:

Yes, I sent it right away, I am guessing it was a mistake too but when we talked on the phone he said 1875, he did not say per acre he just said 1875 so I assumed it was 150 per acre but when the offer came and it said 1875 per acre I was no doubt over joyed! If it was an error is that something they could be accountable for?

Thanks! When I saw the bonus I didn’t try to negotiate the 1/8 royalty because I figured I would make most of my money up front.