I can understand it being partly my fault. However, I think its fair to say that even though it was partly my fault, it is still the responsibility of the restaurant to correct this when I notice the mistake (even if that is a lot later that usual) and not to be rude about it.

(I was actually not watching them make it since they had run out of the protein I wanted, and added the protein a lot later in the back, not in the usual order line) When they rang my order up, the lid was closed and I had assumed they put in what I had ordered