Other complainants shared the same views, the authority said.
TVNZ told the authority the ad was shown during the film as a result of "human error".
"We understand that it played in the wrong place at the wrong time and we are very sorry that we didn't pick this up before it went to air," TVNZ told the authority.
"The programme's subject matter wasn't taken into account and it should have been. This was due to human error and wasn't a deliberate decision; however the fault was ours and it shouldn't have happened."
It was reviewing its ad booking processes as a result, the broadcaster said.
The authority said the ad placement should have been considered before the broadcast.
But it settled the matter because of the broadcaster's apology and review of processes.
Brad Shipton and Bob Schollum, former police officers, and Clint Rickard, who became Assistant Commissioner, were found not guilty of raping Ms Nicholas.
Shipton and Schollum were already jailed for the rape of another woman. Detective Inspector John Dewar was convicted of four charges of attempting to obstruct or defeat the course of justice and jailed for four-and-a-half years.
- additional reporting New Zealand Herald.