Warren Gatland admitted that he feared the worst after seeing the replay of Tomas Francis' contact with Dan Cole's eye.
Francis was penalised by referee Craig Joubert after extensive television replays, with Joubert saying that there wasn't enough footage to issue more than a penalty at the time, but that a closer look would be had after the game.
"I haven’t seen it again, but I listened to the TMO’s commentary of it and he said that there was only one view on it and it was inconclusive He said that he thought that it was contact to the face and that he thought that it was a penalty," Gatland said.
"To be honest my initial reaction was that I didn’t think that it looked great. That was my initial reaction but I haven’t had a look at it again since then."
Wales failed to score any points until after 50 minutes with Dan Biggar's chargedown try, after a poor first half in which they missed 19 tackles.
"It is not acceptable if there was a lack of energy or effort in that first half. We just need to see why that was or why they felt a bit flat," added Gatland.
"So I’ll be talking to individuals to ask those questions because at this level when you are doing what you are doing and there is so much at stake you have to have the right emotional state as you take to the field.
"I’ll be pretty thorough in terms of questioning our preparation for the week and look at what we could have done better as coaches and as a management and the players hopefully themselves are pretty honest about their own performance particular in that first half."
Gatland provided a positive update on captain Sam Warburton, saying he was up and about in the changing room and would go through the concussion protocol this week.
The Wales head coach was also keen to praise England for their performance, adding they were more "desperate" for the result.
"England are always a tough side, I think that this is the 12th time that I’ve played against them – we’ve won six and we’ve lost six and they’ve been knocking on the door for the last three or four years and haven’t been able to get across the line and they came out with what we expected them to do," he said.
"England were accurate, strong on the ball, put us under some pressure and unfortunately we didn’t respond in the first half. We were much better in the second half which is what was really disappointing from our point of view. They’re a good side with a huge amount of depth and there’s always no more than a score to two between the teams.
"We spoke at half-time about making sure that we got our emotional state right, like I said we looked flat and played that way in the first half and that reflects in the way that your line speed is defensively. So we weren’t coming off the line, we got caught on our heels on a few occasions and got beaten by some footwork and England punished us in that first-half.
"Unlike us we missed a few tackles and it put us under some pressure. I’m not taking anything away from England I thought that they were outstanding and the deserved to win the game and good luck to them.
"I thought that they were more desperate than we were today and they seemed to want it a little bit more. Owen Farrell did a great job with kicking their goals and being able to hang on to win it."