Just two minutes after Mikael Forssells fourth goal of the season put Blues into the lead Dunn made a dart into the box from the right-hand flank and was clearly up-ended, as tv pictures showed, by Wanderers midfielder Ivan Campo.
The referee however waved away appeals for a spot kick and duly booked Blues' record signing for diving, a decision Bruce is hoping the St. Helens official will reconsider.
"I hope the referee has a good look at it and says he's made a mistake," said Bruce after the game.
"Its a penalty and unfortunately Dunnies been done for diving and the referees genuinely made a mistake.
"Today it doesn't really matter but I hope he has a good look at it and takes away the yellow card."