The Blues claimed the series 2-1 with a 30-12 win at Suncorp Stadium on Wednesday night, but a furious Smith raised concerns as to whether Bradman Best's breakaway try in the 57th minute should have been awarded.
As Queensland peppered the NSW line with a kick to the air, Jojo Fitita challenged Blues winger Jack Bostock to claim the ball.
Neither player could gather possession cleanly but replays appeared to show both players touched the ball before it fell forwards, away from the NSW line, and Best scooped it up.
If Bostock had got a touch to the ball the try would have been denied for a knock on.
The NRL relayed through the Nine Network's commentary that a corner flag post camera had cleared Bostock of a knock-on.
But soon after full-time the NRL confirmed what most of Queensland thought they had seen.
"After reviewing all available angles, the bunker did not believe there was sufficient evidence to overturn the on-field decision," a statement read.
"Upon detailed review after the match, the NRL believes that while it was an extremely tight decision, the ball appeared to be touched."
That validated Smith's earlier cynicism.
"If that's touched his hand and it's proved to have touched it, we need a serious review of the bunker," the former Queensland captain said on Nine's post-game show.
"I'm disappointed that Queensland lost. Would that have changed the result? Probably not. But it was at a pretty crucial point in the game.
"For the sake of the game, and I mean the NRL, the sport in general, I hope he hasn't touched it.
"I really hope he hasn't, but if he has, we need to sit down as a sport and make a decision on where we head with this bunker.
"We spent a lot of money on it. We put trust in people to sit in there and make the right decision.
"If we're not going to make the right decision in the big games, in the big moments, flick it."
Smith's fellow Nine pundit Andrew Johns also had doubts over the decision to award a try but often was critical of slow-motion replays informing crucial calls.
"Show it in real time, and if it looks like a try, get on with it," Johns said.
"But when I look at it, it does look like it gets a touch."
Speaking on ABC radio, former Blues enforcer Luke Lewis said: "I can see his fingers move ... I'm so glad it was passed as a try, but I think Queensland were ripped off".
Maroons coach Billy Slater, who hadn't viewed clear footage of the incident, said it was representative of a night when "things didn't go our way".
The hosts conceded three penalties to the Blues' five and gave away four ruck infringements to the visitors' three.
But a miffed Maroons captain Cameron Munster felt the need to speak to referee Ashley Klein at halftime.
"I had some questions around certain things ... it was a frustration point in the heat of the moment, asking Ash some questions and he saw it a little bit differently," Munster said.
