TL;DR: For example, this article showed that consistent planning assumptions are more difficult to establish as a result of differences in culture and business tradition, not only between domestic and foreign operations but also between foreign operations themselves.
Abstract: Multinational strategic planning differs significantly from planning purely for domestic operations. There are differences in distance, culture and language which must be taken into account; markets are no longer essentially homogeneous but fragmented and diverse; the collection of market data is often difficult and the data itself suspect in accuracy; the environment in which business operates is also likely to differ from country to country, while the ability to manage political factors becomes much more important; and business is conducted in a variety of currencies which are themselves subject to varying values rather than in a single currency. Consistent planning assumptions are thus more difficult to establish as a result of differences in culture and business tradition, not only between domestic and foreign operations but also between foreign operations themselves.