The first feature film granted permission by the Chinese government to be filmed in the Forbidden City. A documentary produced and directed by Lucy Jarvis for NBC Films Ltd. in 1973 named "The Forbidden City" was the first western film permitted to film within the Forbidden City.
An Italian chef was brought in to cook for the international cast. He brought with him 22,000 bottles of Italian mineral water, 450 pounds of Italian coffee, 250 gallons of olive oil and 4,500 pounds of pasta.
When Johnston is about to board a ship to England 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.
When Johnston and Henry 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.