Ashley Young had a third incorrectly ruled out for offside, City took advantage almost immediately, leaving the game on a knife-edge.
"Intensity, passion, competitiveness...everything was there," Ferguson said. "The incident with Ashley was disappointing because from 3-0 up it went to 2-1 in minutes.
"Football can kick you in the teeth that way. But there will always be controversy in a match like that because there are so many things happening."