Mings picked up the ball after Emi Martinez had taken his goal kick, not realising the referee had blown for it to be taken. Hans Vanaken then converted the resulting penalty for the Brugge win.
"It is very strange this mistake, but it is football," Emery said in his post-match press conference. "It’s the biggest mistake in my career as coach.
"We can make a mistake in the build up, but we work to try and control the games through possession. We did the first half fantastic.
"We lost one or two balls, but this mistake is very, very strange. It’s not for Tyrone Mings or Emi Martinez. It’s only happened one time in all my life. Today."
Asked if he had spoken to Mings about it, he said: "We have to forget quickly. This mistake is not going to repeat again, I think never in my life."
Villa defender Ezra Konsa also said: "It is part of football. Our first loss in the Champions League and we have to move on, we cant be too down about it.
"I didn't see it, I just saw the players running to the referee saying handball.
"It kills the game. If it is a handball, a deliberate one, why not give give him a second yellow? It is a mistake but we have to learn from it."