The NRL have revealed Brisbane Broncos' forward Patrick Carrigan should never have been penalised or sin bin for his alleged hip drop tackle against the Melbourne Storm on Thursday evening.

Carrigan, who wasn't charged for the incident on Friday morning by the NRL's match review committee, was sin binned by referee Todd Smith for an alleged hip drop against Melbourne Storm prop Nelson Asofa-Solomona, who came up clutching at an ankle.

It followed controversy during the first half, when Reece Walsh wasn't penalised for a shoulder charge, and Herbie Farnworth was awarded a penalty try in the next set.

Brisbane, who went on to lose the game, played through the ten minutes without Carrigan, and coach Kevin Walters was less than impressed post game.

The NRL's head of football Graham Annesley said at his weekly media engagement on Monday afternoon that some tackles with hip drop actions simply aren't hip drops given where the defenders body lands. In this case, Carrigan's body landed on the ground, rather than on the Kiwi prop's legs.

"We are seeing hip drop tackles with hip drop actions that are not hip drops. Unfortunately, this is one of those given the decision that was made on the field," Annesley said during Monday's footy briefing.

"Whether players get injured or not, it is a factor in relation to match review and the grading of charges once an offence has been commited or determined. It can also be an indicator to the referee that stronger action is taken if a player is injured as a result of an illegal act.

"Players do get injured in accidents from time to time. It's unfortunate, but it does happen. Injury here is only a factor for the on-field officials and the match review committee if it's an illegal hip drop tackle.

"If we look at this back view, I'm the first to admit this has the elements of a hip drop - there is a grab, a twist and the body is dropped to the ground. But the critical factor is where his body lands, and in this case he [Patrick Carrigan] falls on the ground with daylight between his body and the legs, so he doesn't fall with his full body weight.

"There is contact under his arm pit, but that's going to happen everytime a player makes a legs tackle, so that's not considered to be a hip drop.

"It [a hip drop] is really about this bottom section of the torso landing on the legs which in this case it doesn't."

Annesley said the NRL and its referees have spent plenty of time going through hip drops, and was frustrated that they got the decision wrong, while also stating he doesn't want the bunker to rush future decisions.

"I'm frustrated when errors are made. I don't believe it's because of any misunderstanding because we have spent a lot of time with the referees and the match review committee on what is a hip drop and what is not. These are errors that are unacceptable, but no one is trying to make errors," Annesley said.

"I'd rather they get the decision right, and clearly they do have time constraints. They can't sit there for ten minutes, but we don't want them making rushed decisions without looking at all the available evidence," Annesley said when asked if he would like the bunker to take longer in making decisions around hip drop tackles.

Carrigan was one of three sin bins for the Broncos during the game, with his ten minutes off the park leading to a try for Justin Olam.