Revealing mistakes: In the scene where Johnston and Pu Yi say "farewell" to each other and as the musicians appear and follow Johnston, reflections are visible in such a way that indicate that the scene was actually shot through the glass of a pre-existing structure. The reflections are not consistent with anything else in the shot.
Anachronisms: When Johnston is about to board a ship out of China to return to England, in a scene set in 1931, a ticket office window is seen in the background with opening and closing times given in simplified Chinese characters. China only switched to simplified characters after the Communists came to power in 1949, with a drive to improve literacy. At the time this scene takes place, traditional full-form characters would have been used.
Audio/visual unsynchronized: When the princess gives birth, you can hear the baby crying, yet when the camera moves across, the baby has a calm expression.
Anachronisms: In the Director's Cut of the film there is a scene, just before the Emperor cuts his hair, in which the consorts are dancing to a song being played on a violin. While this scene takes place some time before 1924, the song is "Ol' Man River" from the musical "Showboat" which did not have its first performance until 1927.
Revealing mistakes: When the Empress Dowager dies, a eunuch covers her face with a cloth. Just before the cloth touches her face, you can see her left eye close.
Factual errors: The tour guide at the end of the film says that Pu Yi was 3 years old at his coronation. This is wrong. Pu Yi was born Feb. 7, 1906 and invested Nov. 14, 1908, aged 2 years 10 months.
Factual errors: Mr. Johnston enters the emperor's service during the 1919 May Fourth student movement. Thus, Pu Yi is 13 years of age, not 15.
Factual errors: At the time when he next sees his mother, Pu Yi says, "My mother has not seen me for seven years." That would make the year 1915, but it is wrong. He should say, "My mother has not seen me for four years," which makes the year 1912. In the spring of 1912, the new republican government divided the Forbidden City by constructing a wall, thus restricting the emperor's domain. Assuming that it is that dividing wall on which Pu Yi and Pu Chieh climb, one must reasonably assume that, since the wall is clearly under construction, the date is mid-1912 at the latest. If so, then Pu Yi has just turned six, not eight, and has been separated from his family for four years, not seven.