The two sides played out a goalless draw at the Britannia Stadium, but Mackay felt Adam should have seen red after pushing Fraizer Campbell over in the box having already been booked.
But referee Michael Oliver booked Campbell and Peter Crouch.
Mackay revealed he has asked Professional Game and Match Officials (PGMO) boss Riley for an explanation into the decision of referee Michael Oliver.
But Mackay insisted he will not be waiting anxiously for a response from Riley, and is happy to accept that officials make mistakes.
"If you look at cold, hard facts he should have been sent off," said Mackay.
"We will see what happens with that one, I have put my request in to the PGMO in terms of clearing up the issue.
"I am certainly not someone who is waiting on apologies from Mike Riley every week.
"I know it has been something you guys (the media) have been driving but it means nothing to me, I don't really care.
"They do the best job they can the referees, sometimes honest mistakes happen."
He light-heartedly added: "Michael Oliver is a good referee and he refereed the game well last night, apart from not giving us a penalty (for a Marc Wilson challenge on Campbell) and not sending off a man, he refereed the game well!"
Mackay also believes a private phonecall between Riley and a manager with a grievance is the right way for such matters to be handled.
He said: "I think it is the clearest way it can be, for the referees' boss to speak to his referee and his assessor and determine what happened after the incident once they have the chance to see television footage.
"Things happen in split seconds, once they are able to reassess on televisions and then the head of the PGMO phones the manager of the team, I don't see how it can be clearer than that.
"From the media's point of view it is a private conversation which probably frustrates the media as they don't get to hear about it unless the manager decides to speak about it."
Mackay also hopes to have Craig Bellamy and Andrew Taylor available to face Crystal Palace on Saturday after the pair sat out the draw with the Potters.
"Craig had a tightness in his hamstring which meant we decided to leave him behind," he said. "He is travelling down to London today to join up with the group.
"We felt it was something that would not be right for midweek but would be right for Saturday.
"Andrew did a fitness test and just failed it, so we will assess that today and tomorrow.
"I have to say young Declan John was immense in terms of how he stepped into another Premier League game and came through it with flying colours."
- Sports & Recreation
- Fraizer Campbell