The visiting midfielder picked up two cautions from referee Nick Walsh inside three minutes as the game exploded in spectacular style with three goals.
McGregor was booked for a foul on Ryan Kent and then again for a late tackle on Glen Kamara in the build-up to Rangers’ opener, chested over the line by Kemar Roofe.
After playing advantage, Walsh, on his own Old Firm debut, awarded the goal and returned to show the Scotland international a second yellow card and make Celtic’s task at Ibrox tougher as the 10 men went on to lose the match 4-1.
And former Hoops midfielder Stilian Petrov, on analysis duties for Sky Sports at half-time, said the midfielder must do better.
Asked about both decisions, he said: “[No complaints] at all. Ryan Kent has been really lively for Rangers and driving at people and making the difference, but Callum McGregor has to do better
“Especially in the second one going down and diving in - you’re one of the experienced players - stay on your feet.
“It’s not a situation where you have to dive in but the momentum carried on for him.”
The Hoops later equalised through an Odsonne Edouard header before Alfredo Morelos emphatically fired Rangers back in front at the break. Roofe’s second and a late strike from substitute Jermain Defoe completed the rout.
Rangers are seeking an unbeaten season having now completed an unbeaten record against their Old Firm rivals for the first time since season 1999-2000.