Is waving the American flag in the park a crime whether it will be detained by the Public Security Bureau? First of all, waving the American flag in the park is certainly not illegal. The first thing you need to do is to get the police to take you to the police station. Because of course there is nothing to this. Nowadays, movies and TV dramas are filmed by private companies, and people can just rent a street and a piece of land. Wearing Japanese military uniforms to say is to shoot TV dramas, people can shoot you can also shoot say the United States and China are diplomatic countries. The two countries have embassies belonging to friendly countries. Now many U.S. companies are hanging in front of the U.S. flag, you can wave it in the park, it is legal. It's just that it might look a little bad to other people.
But from a legal point of view, because the law does not stipulate that the use of other flags is not allowed in addition to the U.S. journalists are more sensitive, if it is only because you are waving the U.S. flag on the departure of the Chinese police, you then the U.S. journalists will surely question the legal basis of China. China will also pay attention to the international influence will not be waving a country's flag to get into a bunch of trouble. Besides, it's not like you're revolting or protesting, you're just having fun or making a video. In the absence of a law explicitly stating that it's forbidden, this is not a crime. Not to mention that you will be detained by the Public Security Bureau.