With 90 seconds left of Saturday's game and Adelaide trailing by a point, former Sun Rankine appeared to take a mark in the pocket but was tackled by Sam Collins and the ball spilled out.
If not considered a mark, Rankine clearly had the case he had been illegally held in the contest and should have been awarded a free kick.
Either way, the star Crow would have had a shot at goal.
But the umpires called play on and the Suns cleared the ball and were able to hold on for a clutch 13.13 (91) to 14.6 (90) win at People First Stadium.
"My version is I think if he didn't mark it, he was tackled in the marking contest," Adelaide coach Matthew Nicks said of the match-defining decision.
"But we made so many mistakes throughout the game. Things happen."
On Sunday, the AFL confirmed it was a mistake.
"With 1.44 remaining in the Gold Coast v Adelaide match Rankine should have been awarded a mark," a spokesperson said.
"Subsequently, he was also held in the marking contest, which should have also warranted a free kick. Upon review, the umpires missed it in real time.
"The AFL football department has contacted Adelaide this morning."
It will be little consolation to the Crows (3-1), who suffered their first loss of the season, while Gold Coast (3-0) continue their unbeaten start.
"That last minute and a half we clearly didn't get things going our way," Nicks said.
"So I sit here as a coach and say, 'What do I preach to the players?'
"I preach about being in the moment, don't blame others, get on with life, you've got to butter up and go again next week, so I'm doing my best to stay in that space.
"I'd say we've got some frustrated fans out there and I feel for them and I'm a little bit with them."
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