At that time private studios didn't have simultaneous audio equipment, and sound had to be dubbed in after. In order to save sound-track, no errors were permitted.
那時候，民營電影公司都沒有同步錄音的設備，所有對白都需要事後配音，老板為了節省聲帶片，不允許有人忘詞、出錯、吃螺絲。