Ronaldo and teammate Karim Benzema both netted twice following their poor start to the season in front of goal.
Nacho and Luka Modric completed the rout, after former Manchester United man Ronaldo spoke out against reporters.
"I say one thing and you write another. So why do you want me to speak?" the forward said.
Ronaldo has scored eight goals in the Champions League this season and manager Zinedine Zidane was confident that the goals would come.
"I am happy for them and they will keep working now. We knew that this would happen, that the goals would come," he told journalists.
Madrid return to La Liga action this weekend when they play Malaga on Saturday.