Galliani had just watched Milan draw 0-0 with Napoli and was on his way to the airport when his car was stopped by around 50 Ultras.
The Ultras refused to let him pass and began to throw stones at his car, breaking a window and prompting his police escort to call for back up.
Fears for Galliani's safety increased when the car got a puncture, leaving it even more exposed to attacks.
Galliani did reach the airport in time, though. He boarded the plane chartered by Milan and discussed the game with Carlo Ancelotti.