Referee Jonathan Kaplan awarded a controversial try to the dismay of the Ireland players
Ireland skipper Brian O'Driscoll insisted the controversial try scored by Mike Phillips of Wales should have been referred to the video official.
Phillips scored from an illegal quick line-out throw-in to help the Welsh record a 19-13 victory in Cardiff.
"It was clearly an illegitimate try and we feel hard done by," said O'Driscoll.
"That is what TMOs are for and I am pretty sure you can go to them, even from that far out. We try to play by the rules of the game."
O'Driscoll, who had claimed the first score of the game to level Ian Smith's championship record of 24 tries, said: "I didn't see it myself but when half your team saying it you take their word for it.
"I tried to relate that to [referee] Jonathan Kaplan and the touch judge and they were having none of it and it's really frustrating for such an incident to have a huge bearing on the game.
"I actually didn't (ask Kaplan to use the video official). When I went over to him he was pushing everyone away and I told him I was captain and he said that was fine but he wanted to talk to his touch judge.
"So I stood there and before anything else could be said he awarded the try.
"I did mention it to him a few minutes later after I had seen it on the TV and I told him that it was a massive momentum swinger and that it had had a huge bearing on the game, but he just shrugged that off.
"Games hang in the balance on decisions, everyone is human and wrong calls are made sometimes, but some are unforgivable."
Ireland coach Declan Kidney said: "There are a lot of people employed to get these things right.
"We have to look to them to do their job. Our job is to pick ourselves up from a disappointing day and get ready for the next match.
"We lost by six points - that was a seven-point decision. It was obviously big in terms of the game, but that's life."