The Danish keeper inexplicably fumbled a corner kick into his own net when under no pressure and the home side hung on to clinch their first victory in five home games.
Pearson said: "In a nutshell, the game's been settled by one incident really, but we've not created enough chances in open play to get back in it in the end.
"No doubt people will dwell on the goal but there will probably be more talk about it outside our dressing room than inside.
"Kasper's been exceptionally good since he came to the club and been responsible for winning matches and picking up lots of points with his performances.
"These things happen and we just have to pick ourselves up for the next match.
"The goal knocked us out of our stride just as we were settling into the game after weathering Doncaster's early pressure.
"I thought our best spell was just before half-time when we were more creative and we hit the post. But when we needed a bit of quality after the interval we let ourselves down .
"The final ball was not quite good enough and that's something I've not really had to speak about this season.
"They won the match fair and square and I'm not going to show any sour grapes. Some of Doncaster's games of late they've been unfortunate not to win so I suppose they are due one .
"We've won a number of times ourselves in tight situations so I'm not going to disrespect what they've done today. It's a blip for us but we've got the international break to get over it and come out fighting again."