Harbaugh said his staff has been submitting questionable calls by referees to the conference this season, and he acknowledged getting a response to this particular game.
"As we all expected, and all saw, mistakes were made," Harbaugh said. "That was the response [from the conference], yeah, they made a mistake."
The call in question came in the second quarter when Michigan defensive end David Ojabo sacked Michigan State quarterback Payton Thorne. The ball was fumbled, and Michigan's Aidan Hutchinson recovered the fumble in the end zone for a touchdown.
The officials in the game reviewed the call through replay and overturned the fumble and touchdown, saying Thorne was down before the ball was loose.
Harbaugh was not happy with the officiating after the game but didn't elaborate any further immediately after the loss.
"No, I made my thoughts known throughout the game," Harbaugh said in his news conference after the Michigan State game.
Immediately after the game, Harbaugh was critical of a no-call on what he thought should have been a pass interference call on Michigan State in the fourth quarter that would've extended a key drive for the Wolverines.
He didn't specify any calls outside of Hutchinson's reversed touchdown that were sent to the conference but said the conference admitted to errors in other plays throughout that game, as well.