NRL Referees boss Tony Archer has admitted that Melbourne captain Cameron Smith was forced to take a conversion from the wrong spot in the Storm's two-point preliminary final win over Canberra on Saturday night.

An altercation after the try was scored forced the referee to move his position and he failed to return to the spot where the try was scored after it was confirmed by the video referee.

"You can see that there is an incident post-try and the referee took up the wrong spot after the try was awarded by the video referee," Archer said.

"The shot should have been taken closer to the goal posts."

Archer confirmed the big decision to sin bin Canberra fullback Jack Wighton was the correct one and consistent with what the referees have been doing all year in regards to long breaks.

"The reason it is a professional foul is that there is a long break made by Koroibete, the referee gets to the ruck and instructs the player to get off the tackled player," Archer said.

"He is entitled to a quick play the ball because of the big break, Jack Wighton holds on and then continues to slow down the play the ball even after Koroibete is ready to play it. It stops play it is a penalty and a professional foul."

Watch the whole NRL HQ referee review below.