The Belgian has made a positive start to life at Liverpool this season, but he made a glaring mistake when he accidentally helped Alvaro Negredo's tame strike into the back of his own net.
Per Sky Sports, Mignolet said of the incident:
It is one of those things that happens, unfortunately, when you are a goalkeeper. Any goal you concede is a disappointment.
I probably should have done better with it. I've been there in the past as a goalkeeper, and you have to accept it and move forward to the next game.
It was a very awkward moment for us just before we went into half-time. It gave them a lift, and we went in being down, but then again, in the second half, we lifted our heads and tried to create as many chances as we could.
While Mignolet will be forgiven for his error, it was enough to cost Liverpool the top spot in the Premier League despite a strong showing in the clash at the Etihad Stadium.
The Reds will point to refereeing decisions also having cost them on the day, with manager Brendan Rodgers set to face investigation over particularly strong words said of official Lee Mason postgame, per Mirror Football's Alan Nixon.
Opposition supporters, though, will point to the numerous opportunities the referee had to award a penalty for shirt pulling by defender Martin Skrtel at corners, which the referee chose to ignore.
Despite defeat, Liverpool fans can be positive about the manner of their side's performance in the encounter and take heart for the rest of the season.
Liverpool have looked sensational against some of the league's lesser sides, but true title challengers are required to also perform against the best outfits in the division.
If there were any doubts about Liverpool's pedigree to beat the top sides, then they were silenced Thursday, with some of the Reds' interplay simply sensational. Luis Suarez, predictably, was at the heart of it all.
Rodgers lacks the strength in depth that some of his top-four rivals have at their disposal, which could prove costly come May. However, when he can call upon the majority of his first-team squad, they are an excellent and much-improved side, even in the absence of Steven Gerrard and Daniel Sturridge as per the weekend.
City's unblemished home record was given a real fright by the Reds, only to be spared by Mignolet and Raheem Sterling, who blazed over a golden chance from just a few yards.
Rodgers' side must now regroup ahead of a weekend clash with Chelsea—a game for which they will need their goalkeeper to quickly clear his mind of any doubt caused by his latest folly if they are to secure a positive result.
Defeat, though, would be a real blow to the side's confidence at what is the halfway point of the 2013-14 season.