In Chapter 1 when Pony is jumped by the Socs on his way home from the movies, they ask him if he wants his hair cut off. He will later get his hair cut off because of a Soc (because he is there when Johnny kills Bob Sheldon).
In Chapter 2, much of the second half of the chapter is a flashback. It is the part where Pony flashes back to what happened when Johnny was beaten so badly by Bob and the other Socs.
Then at the end of Chapter 2, the very last line could be called foreshadowing too.
In Chapter 2, Johnny gets severely beaten by a group of Socs to the point that he is nearly unrecognizable. When Ponyboy and the other Greasers discover Johnny lying motionless across a field, his face is covered with bruises and cuts. Johnny then explains to the Greasers how a group of Socs hopped out of a blue Mustang and jumped him. Ponyboy goes on to mention that Johnny always carries a switchblade with him wherever he goes after suffering that severe beating. Ponyboy foreshadows Johnny's unintentional murder of Bob Sheldon by saying,
He'd use it, too, if he ever got jumped again. They had scared him that much. He would kill the next person who jumped him. Nobody was ever going to beat him like that again. Not over his dead body.
Ponyboy again foreshadows Johnny's unintentional murder of Bob Sheldon at the end of Chapter 3 by saying,
Things gotta get better, I figured. They couldn't get worse. I was wrong.
In Chapter Four, Ponyboy and Johnny are jumped by a gang of Socs, who attempt to drown Ponyboy in the fountain located in the park. Johnny ends up saving Pony's life by stabbing and killing one of the Soc members. Unfortunately, Johnny is forced to flee the city and Pony travels with him to Windrixville.
In Chapter Seven, Ponyboy includes a flashback to explain Darry's personality. One time, Steve made the mistake of calling Darry "all brawn and no brains," and Darry broke his jaw. Steve learned his lesson to never call Darry that again, and Darry never forgave Steve for his comments.