Lord of the Flies is a novel about a group of British boys who become stranded on an uninhabited island and attempt to govern themselves, with chaotic results. Crash is a film about the problems faced a number of people in Los Angeles and their experiences as they navigate a complicated set of race relations in their city.
These two works are quite different, but both are similar in their analysis of how people create inequality and other social problems in society. Lord of the Flies exhibits how a violent and chaotic society arises from a group of young boys attempting to govern themselves and the tension between the desire for power and desire for social order. Crash examines how individuals from different racial backgrounds interact and use these interactions to justify their own beliefs biases. Both of these works examine the individual and interpersonal impact of problems within a society, whether those problems are due to the inherent tensions of trying to develop a fair and ordered new society or the existing tensions of racial inequality and stereotyping.
Additionally, both Lord of the Flies and Crash utilize a limited setting to convey themes relevant to all of society. Lord of the Flies is limited in setting to the island, while each of the intertwining stories in Crash takes place in the city of Los Angeles. Both works use limited settings as allegories for larger problems within society.