"World Rugby has clarified to the Wales team management as part of the usual review process with teams that the TMO made an error in the application of law during the England versus Wales match at Twickenham", they said.
A similar event was staged before the 2017 autumn Tests against Wales, who England beat 12-6 on Saturday.
England coach Eddie Jones questioned the point of the admission because, in retrospect, it can't change anything.
Asked if he will issue a formal complaint about the decision, Gatland replied: "I will just get clarity. The game's done and dusted, so we've got to trust the referees and respect their integrity". "It is always a chance lost when it is a one-score game".
Wales assistant coach Rob Howley said it was "disappointing" but that "there was plenty of time after that decision".
"Every scrum has to be intense otherwise you get folded up like a travel map stuffed in your back pocket", said Hartley. If you haven't got the rub of the green, then you know you probably get it in the next couple of games.
The England against Wales game was the closest contest of the second round and the game was overshadowed by a TMO decision which saw Wales not awarded a try. The TMOs do an excellent job.
Jones' squad is made up largely of the same players that have featured in the championship so far this month, with loosehead prop Joe Marler joining Haskell in returning from suspension, while Hughes is included after making his comeback from a two-month knee injury in Wasps' 44-22 victory over Harlequins on Sunday.
"We want to have the best scrum in the world and they are the biggest, ugliest, strongest scrum pack in the world, so it's fantastic", Jones was quoted as saying on the RFU website (www.englandrugby.com).
"Georgia were just the sort of scrum we needed to scrum against - strong, scrummaged in a different way", Jones said.
"We will throw everything at them and play the style we have been playing". Now, he is using his contacts with Georgia coaches Milton Haig and Richard Graham, who are from New Zealand and Australia respectively. "They scrum for a living and our guys have learnt a number of different things".