The advent of Massive Online Open Courses (MOOCs) has led to the availability of large educational datasets collected from diverse international audiences. Little work has been done on the impact of cultural and geographic factors on student performance in MOOCs. In this paper, we analyze national and cultural differences in students' performance in a large-scale MOOC. We situate our analysis in the context of existing theoretical frameworks for cultural analysis. We focus on three dimensions of learner behavior: course activity profiles; quiz activity profiles; and most connected forum peer or "best friends." We conclude that countries or associated cultural clusters are associated with differences in all three dimensions. These findings stress the need for more research on the internationalization in online education and greater intercultural awareness among MOOC designers.