Reds boss Richard Graham and captain James Horwill both voiced their frustrations over the refereeing at the breakdown against the Sharks.
The Reds battled back from a 25-6 deficit at half-time to 28-20, before Beau Robinson was sin-binned and Dale Chadwick scored the Sharks second try.
That yellow card was viewed as a key moment by Graham, who was unhappy with Lourens van der Merwe's officiating around the ruck.
"At that point [the sin-binning], we still had an opportunity. We finished strongly, so it would probably have come down to how we managed the last 13 minutes," said Graham.
"I don't think the breakdown was refereed very well, so I'm frustrated in that sense.
"Those guys know themselves they missed opportunities, so I don't need to say anything to them.
"Our character, when we were down 25-6, was displayed when we came back to 28-20. But our accuracy has got to be better."
Horwill added that while the Reds may have felt hard done by in certain areas, it was purely the nature of the sport.
"There were certain things that we didn't get the rub of the green, but that's rugby sometimes," said Horwill.
"There were plenty of opportunities either side of half-time to get closer, and we just didn't take them."