(at around 48 mins) Sir Charles Chaplin devoted eight days to filming the department store roller-skating scene where he skates blindfolded on the edge of the fourth floor, coming within inches of falling over the edge into the deep stairwell below. The dangerous large drop was actually a painted scene on a pane of glass carefully placed in front of the camera to align with the existing set and create the illusion of great height.
(at around 1h 25 mins) Discounting later parodies and novelty films, this was the last major American film to make use of silent film conventions, such as title cards for dialogue. The very last dialogue title card of this film (and thus, it can be said, the entire silent era) belongs to The Tramp, who says "Buck up - never say die! We'll get along."
The film originally ended with Sir Charles Chaplin's character suffering a nervous breakdown and being visited in hospital by the gamin, who has now become a nun. This ending was filmed, though apparently only still photographs from the scene exist today (they are included in the 2003 DVD release of the film). Chaplin dropped this ending and shot a different, more hopeful ending instead.
(at around 1h 20 mins) Sir Charles Chaplin allows the Tramp to speak on camera for the first time during the restaurant scene, but insisted that what the Tramp says be universal. Therefore, the song the Tramp sings is in gibberish, but it is possible to follow the story he tells by watching his hand gestures.
This was always intended to be Sir Charles Chaplin's first talkie. He even went as far as writing a dialogue script and experimenting with sound. However, because Chaplin intended the film to feature his Little Tramp character, sound seemed inappropriate. Consequently, the film was made using silent techniques, shot at 18 frames per second and then projected at 24 frames per second, which gave the slapstick sequences a more frenetic feel.
Charles Chaplin: [dream sequence] There is a fantasy sequence showing a domestic life for the Tramp and the Gamin.