No time travel
Yes, you are not able to travel through time in whatever movie you make in China, it is considered disrespectful and frivolous towards history itself. The last thing they want to do is not show history the respect it deserves and want to keep it as pure and factual as possible.
That was sarcasm because the Chinese government has been known to erase parts of history that do not match their political values and even destroy ancient artifacts. We do not see what the big problem of traveling back and forth in an adventure film is, it’s all science fiction and for fun as far as we see it.