The 'incident' to which Ali refers
At one point in the film, while explaining to Emmi the increasing hostility he feels as a guest worker, Ali alludes to some recent (at the time) xenophobia-stoking incident.
No details are given -- presumably any German audience member in 1974 would have understood the reference.
Anyone able to shed some light on the relevant history? The incident was simply referred to as "what happened in [Munich / Hamburg]" (I can't remember which).