Continuity mistake: When the Empress Dowager dies, she can't stand opening her eyes and closes them as the servant covers her face. You can see that through the white cloth.
Other mistake: The documents to which the Imperial Seal was stamped at both the coronations in Peking (1908) and 'puppet' coronation in Manchuria (1934) carry the same dates. They also show the same 'coronation names' when it is known that Puyi was coronated as 'Xuantong' in Peking and 'Kangde' in Manchuria. This will only be apparent if one can read Chinese. (00:14:45 - 01:47:40)
Continuity mistake: When the new bride is kissing Pu Yi, she leaves some lip marks all over his face, but these marks change from shot to shot.