What are some examples of foreshadowing in Chapter 3 of the outsiders?

Ponyboy and Johhny walk Marcia Marcia and Cherry to fetch a car. Once again, the blue Mustang appears, but this time it stops beside them and Bob and Randy get out. They start defending themselves to their girlfriends, at first ignoring the Greasers. Randy refers to the guys as "bums," and Two-bit gets defensive. He breaks the end off a bottle and hands it to Ponyboy, then flips out his own switchblade. This foreshadows the fight in the park when Johnny kills Bob.