Gareth Anscombe saw a try ruled out in the first half at Twickenham, despite replays suggesting he beat Anthony Watson to ground the ball.
Sam Simmonds will miss this week's training camp in west London due to the shoulder injury that he suffered in the 12-6 victory over Wales last Saturday, but the back-row injury problems that England entered the championship with have been somewhat alleviated by the return of James Haskell and Nathan Hughes.
Following a review, World Rugby said Tuesday it has "clarified to the Wales team management. that the TMO made an error" and that "Wales should have been awarded a try as the Wales player grounded the ball".
England head coach Eddie Jones also recalled British & Irish Lions forwards James Haskell and Joe Marler who were suspended for the opening two rounds.
Asked if he will issue a formal complaint about the decision, Gatland replied: "I will just get clarity".
No one can categorically state that Wales would have won the game if the try had stood but it would have changed the complexion of the game without a doubt and it's possible we could be looking at a different Six Nations table.More news: Mendis replaces Perera in Sri Lanka squad
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"The TMO has one big decision to make and unfortunately he's made a bad mistake". You could see on the replay that Anscombe got there first.
But Police Scotland said: "Following an initial report of sexual assault in Edinburgh city centre during the early hours of Monday 12 February, police conducted various lines of inquiry, including speaking to a number of potential witnesses".
However winger Alex Cuthbert is out, because of a knee injury.
"We have said to him if you want to play for England and you are good enough we will select you", said Jones.
Sam Simmonds could miss England's upcoming Six Nations global away to Scotland after being omitted from the squad selected for this week's training camp in London. They came rolling down the M4 full of confidence, very cocky, and it was important that we started the game well and took a bit of wind out of their sails, which we did. They understand the game and they've got vast experience.
That they then failed to trouble the score again for the next 60 minutes was a tribute to Wales. Now, he is using his contacts with Georgia coaches Milton Haig and Richard Graham, who are from New Zealand and Australia respectively.