Previous Celtic managers Tony Mowbray, Gordon Strachan and Martin O'Neill were on one-year rolling contracts and are all believed to have had higher earnings.
But Munster held firm and when they went back on the attack just after the hour Pelous, who had just come back onto the pitch, was again penalised, this time for not rolling away in the tackle, and O'Gara kicked Munster back into the lead.
Italy prop Carlos Nieto was sin-binned for not rolling away at a ruck after 12 minutes and O'Gara got the visitors on the scoreboard with a simple penalty.