Mbappe, who had scored a goal, was furious to get replaced by Mauro Icardi within the half.
The PSG striker tried to dismiss manager Thomas Tuchel, who was attempting to talk to him, and so dismissed a coach who tried at hand him a jacket before skulking to his seat on the bench.
Neymar needed prolonged treatment once being cut by Montpellier’s Arnaud Souquet towards the end of the first half and angrily remonstrated with the fourth official within the tunnel at half-time.
That drama aside, it had been a comfortable win for PSG against a side who finished with 9 men.
Pablo Sarabia curled PSG into a lead before away keeper Dimitry Bertaud was sent off for handling outside the box.
Angel di Maria chipped debutant keeper Matis Carvalho to double the lead before a Daniel Congre own goal.
Mbappe and Layvin Kurzawa conjointly scored and Joris Chotard was shown a late red card for a foul on Presnel Kimpembe.
Second-placed Marseille visit Bordeaux on Sunday.