Cooper Cronk faulted Penrith's players for turning away as Newcastle took advantage of a penalty restart in their 22-14 preliminary-final win.
On Fox, Cronk said: "The most disciplined team we've seen in a long time. (Moses) Leota had his back turned and Sandon Smith decided to turn and go and has turned this prelim final on its head."
Sandon Smith's first try came after referee Gerard Sutton awarded Newcastle a penalty for a high tackle.
Some Panthers protested that a quick tap should not be allowed after foul play, which usually prompts a Bunker review for possible further action.
The foul play was cleared quickly, and Sutton allowed Smith to restart from the mark while Penrith's players were not ready.
Explaining his decision to captain Isaah Yeo, Sutton said: "It wasn't quick. Foul play has been cleared. You had a chance to reload."
Leading commentators also backed the decision, saying: "Looking at it, it wasn't really a quick tap."
"It was just quicker than what the Panthers thought was about to happen."
They added: "The penalty restart can be a kick for touch, or a tap kick. It looks like he informed the referee he was tapping the ball. The referee had no reason to stop him. He allowed the ball to be put back into play. Panthers turned their backs on the ball. They paid the price."
Leota, Lindsay Smith and Mitch Kenny were identified as the main players caught out, with Dylan Edwards less culpable.
Others called the lapse "inexcusable" and "unprofessional", particularly given Penrith's standards over the past seven years.
Smith later scored again, completing a late double that sent Newcastle into the grand final.