what happens at the end of the party as the guests are leaving in the great gatsby

The party is an example of the excess of the "roaring twenties". Many people are drunk. An unnamed driver and Owl Eyes crash into a wall and end up in a ditch. People stop to gawk and say silly things. Eventually drunk people are trying to drive out and cars are honking. The scene becomes chaotic and violent. It's almost a metaphor for the novel.