The 46-year-old was found guilty on all counts despite protestations by his defence counsel that the jury foreman had lost control of the jury and didn't understand questions asked by the court registrar.
The defence counsel also expressed concern about a question asked by a jury member after they had returned three out of the four guilty verdicts.
The juror, who was not the foreman, asked the judge about the count of making threats to kill. He asked whether the prosecution had to prove their case beyond a reasonable doubt or whether they should decide the case based "on what we believe."
Defence counsel Bernard Condon SC said it was concerning that the jury had asked such a question after already finding the accused guilty of rape, sex assault and false imprisonment because they may have approached those verdicts on the basis of a lack of understanding of the requirement to prove guilt "beyond reasonable doubt."
After being told they must believe the allegations beyond a reasonable doubt, the jury resumed their deliberations and returned shortly afterwards with another guilty verdict.
It is highly unusual for a juror other than the foreman to ask questions of the court but the juror said he had been delegated to ask it.
Earlier, when one of the other verdicts was being read out the foreman seemed confused when asked if it was a unanimous or majority decision. He replied that it was a unanimous verdict but the rest of the jury shouted in unison that it was, in fact, a majority verdict.
Mr Condon said it is concerning that the jury were collectively addressing the court.
"The foreman seems to have lost control of the jury," he told Ms Justice Iseult O'Malley. "And he doesn't seem to understand the questions asked of him by the registrar."
He asked the judge not to accept the verdicts of the jury on the basis of their behaviour and the question about reasonable doubt.
Prosecuting counsel Patrick Marrinan SC objected to this and pointed out that the verdict finding the accused guilty of rape had been returned without any confusion. He added that the question about reasonable doubt related only to the threat to kill count and not the others.
Ms Justice O'Malley agreed with the prosecution and refused the defence application. She said she could see where Mr Condon was coming from and told him he may be able to bring a motion to "arrest" the proceedings before the accused's sentence date.
However she added that she is not even sure if that is legally possible. Mr Condon said he would research the matter and applied for the written transcript of the trial which was granted.
He also applied for bail for his client pending sentence, saying that he has abided by his bail terms since his arrest. Ms Justice O'Malley refused this because the man was facing a "significant sentence". She remanded him in custody until December 17.
The jury returned the guilty verdicts after seven hours deliberation and a seven day trial.
The man had pleaded not guilty to rape, sexual assault, false imprisonment and making threats to kill at his Westmeath home on January 08, 2010.
The trial heard he met the then 19-year-old victim in a local nightspot and seemed to be chatting her up. When the victim told him she was a lesbian he replied that he was also gay.
He invited her to a party in his place that night but when she went back there was nobody else there. As she went to leave, he grabbed her by the arm and flung her back into the room. She said his mood had changed completely and he looked "terrifying".
"You could see the anger in his eyes and I knew something bad was going to happen."
She started hitting him as best she could but he was too strong. He took her into the bedroom, ripped off her clothes and raped her, she told the court.
He told her: "Five minutes of this won't kill you, but if you don't do what I say, I will".
He made her perform a sex act on him and threatened to kill her if she didn't stop resisting. He also threatened to poke her eye out.
She told the man he was raping her but this didn't stop him. She begged him to stop but he responded "it's grand" and "I'm not hurting you." She said as he raped her it felt like she was being punched.
After a few minutes he stopped, sat on the bed and began crying. He said he was sorry and that she had to forgive him.
She said he said something about being "stoned" and asked her if she would go out to dinner with him.
She said she comforted the accused because she was afraid of him but then fled the house. It was almost 5am when she phoned her father and asked him to come get her.