Ferguson shuffled his squad knowing United had already booked their place in the knockout stages and they were undone by Burak Yilmaz's second-half goal.
The Red Devils boss was disappointed to see his side concede from a corner admitting he feared Galatasaray would pose the biggest danger from set-pieces.
"Their temperament was good, the crowd never affected us and I thought they put up a reasonable show," Ferguson told Sky Sports.
"Some of the possession was good, some of the attacking play at times was good without finishing the game off with one or two opportunities in both halves.
"But when you lose a goal from a set-piece you are always going to be saying it's a bad way to lose a goal.
"They had a few strikes from outside the box which our goalkeeper dealt with well, other than that I thought we handled it OK.
"I think if there was one part of it we were going to worry about was set-pieces because they are a more experienced, stronger, bigger side and you expect them to cause you some problems at set-pieces.
"We handled it quite well throughout the match, but we have lost a goal from a corner. It is not surprising because of the strength they have there, but nonetheless to lose a goal from a corner kick is never easy to take."