The Ibrox side were leading through Joe Aribo's first-half goal when Dundee attacker Paul McMullan was brought down as he attempted to burst pass the flailing keeper in the box in the 59th minute.
A penalty was awarded but McLaughlin escaped with a yellow card - seemingly on the basis that he was deemed to have made a genuine attempt to win the ball - and then stood firm to save Jason Cummings' spot-kick.
McPake felt referee Bobby Madden got it wrong and was shown a red card for protesting the decision at full-time.
Asked if he felt McLaughlin should have been on the pitch to save the penalty, the Dundee manager said: "In my opinion, no. I know the rule is if you make a genuine attempt, and people will disagree and say it's a genuine attempt.
"But Paul McMullan is clearly by him and the leg comes out.
"If it's (Dundee keeper) Adam Legzdins would my answer be different? Probably not.
"I am just giving an honest opinion. Having seen it back, I think the arm catches him as well. TV footage will maybe show that better. I am looking at it from a high camera.
"We miss the penalty but we would still have half an hour to play with 11 v 10. I like the rule that if you make a genuine attempt it's not a red card offence but Paul McMullan is clearly by him by the time he makes an attempt."
Regarding the disagreement with referee Madden which resulted in him being shown a red card, McPake said: "I got an explanation out of Bobby. I have a fantastic relationship with Bobby.
"In the end, he became unapproachable and said 'I am not speaking to you about it, I can't talk about an incident' and then you get the 'you missed the penalty anyway' shout. We know that, I watched it."
Dundee have now failed to win any of their first seven league games, but McPake felt his side were worthy of at least a point.
He said: "Both sides made it a really entertaining game. I feel like a broken record but we should have come out of the game with something. I am extremely proud of my players, the way they handled a very good side but gutted for them that they have come away with nothing.
"It's the champions, the best team in the country and they will go away knowing they were in a hard game. We go away with nothing again, which is extremely frustrating, but I can't ask for any more effort. Quality, maybe, in certain areas of the pitch.
"We had other chances as well, so we can't put it down to the penalty."
Dundee's hopes were not helped by the fact striker Leigh Griffiths had to be replaced after 39 minutes with an ankle injury.
McPake said: "It's something that will have a chance to clear up over the next week."