Jean-Claude Van Damme, Abdel Qissi, and Brian Thompson played together in another movie, Lionheart (1990).
The 'Ukrainian' policemen shown at the beginning of the movie speak Russian with heavy Bulgarian accent. It is so, because the sequence was shot in Bulgaria, using Bulgarian extras, uniforms, cars, etc.
Professor Cafmeyer's office is obviously located in the building which houses both the Bulgarian Court of Justice and the Bulgarian Ministry of Justice in Sofia. It is clearly recognized by the large stairs and the big bronze lion statues at the main entrance.