Complex sentence: They stop at a roadhouse bar, not realizing it has an exclusively black clientele, and are intimidated by the hulking patrons; they flee, damaging Flounder's borrowed car and leaving their frightened dates behind.
Split into simpler sentences: They stop at a roadhouse bar, not realizing it has exclusively black clientele. A couple of hulking patrons intimidate them and they quickly exit, damaging Flounder's borrowed car and leaving their frightened dates behind.