With the exception of 'Chris Pedersen' and Bill Coyne, the kids in the movie were not professional actors.
The Rejected Kids hangout was an area of condemned housing that was going to be demolished to make way for the construction of a freeway to LAX.
The homes where the TR kids live were condemned under eminent domain to make way for the Century (Interstate 105) Freeway, which wasn't finished for almost 15 years. The freeway they eventually built was featured in "Speed" as the freeway under construction where the bus has to jump the unfinished chasm.
Penelope Spheeris cast real punk rockers instead of seasoned actors in the interest of realism.
The scene where Razzle shoots a cockroach cost $50, and was one of the most expensive in the film. The insect was specially trained and had its own handler.