WHAT is Jackie Chan doing on the rooftop of a steam locomotive hurtling through a corn field? Why is Tsui Hark in the Forbidden City surrounded by 2,000 lion dancers? Or Michelle Yeoh atop a Ming Dynasty funeral pyre? They are part of a cinematic exodus to the People's Republic of China, the result of an open door through which Hong Kong-originated winds of change are already beginning to transform the face of Mainland Chinese cinema.
At the current rate that movies are produced in Hong Kong, some 500 features will be completed between now and the territory's reversion to Chinese rule on July 1, 1997.
And if the current trend continues, a growing percentage of these comedies, kung-fun pictures, and costume epics will be filmed across the border.
''In terms of movies, '1997' will be more a case of Hong Kong affecting China than the other way around, particularly in the areas of production and distribution,'' says Chan Pak-sang, editor-in-chief of City Entertainment, Hong Kong's leading film journal.
''Over 20 Hong Kong film crews have gone up north to shoot this year so far, and it is inevitable that this continued exposure to Hong Kong technique will have a cumulative effect on Chinese technique.'' W. D. Yang, a Beijing production co-ordinator, concurs. ''The Hong Kong crews come here with their advanced equipment, cranes and cameras that Chinese studios cannot afford at present. But they make us aware of these advancements, things which some of the older film-makers resist but which the new generation of movie technicians are eager to try.'' Ann Hui, a Hong Kong director who produced the Qing-era martial arts saga Fong Sai Yuk in Beijing, noted a keen interest in China on the way her crew executed the action sequences. ''They very definitely use Hong Kong movies as a model, especially the way the shots are set up and the manner in which stunts are done.'' But not all Chinese film-makers regard Hong Kong movies as a learning vehicle. ''Sure, Mainland studios and crews like working on Hong Kong productions,'' says film director Xie Fei, former principal of the Beijing Film Academy.
''But not necessarily for the educational opportunities. It's mostly a matter of money. The remuneration is so much higher that local productions were sometimes finding it hard to book studio facilities and personnel.