The scene where The Lone Prospector and Big Jim have a boot for supper took three days and 63 takes to suit director Charles Chaplin. The boot was made of licorice, and Chaplin was later rushed to a hospital suffering insulin shock. The boot was made by the firm of Hillaby's in Pontefract, West Yorkshire, England; Pontefract is famous for growing licorice and making it into "Pomfret [Pontefract] Cakes".
A real American Black Bear was used for the scene where the "Lone Prospector" encounters the beast. This was unusual for the time, when it was normal for very phoney-looking costumed men to play large animals.
This movie was re-released in theaters in 1942 with a new musical score. Much of the new music was written by Charles Chaplin himself, in collaboration with musical director Max Terr. Chaplin also added sound effects to the film, and replaced the silent movie title cards with descriptive voice-over narration (the 1942 version is included in the two-disc Special Edition DVD of the film). The new release received two Oscar nominations in 1943: Best Music Score of a Dramatic or Comedy Picture and ironically for Best Sound.
In his autobiography, Charles Chaplin revealed he had the idea for this film at Pickfair, the home of Mary Pickford and Douglas Fairbanks. Indeed, his two friends and associates were showing him pictures of Alaska and Klondike. One of them was picturing prospectors climbing the Chilkoot col, which gave Chaplin the subject of his next movie.
At the time of filming, Charles Chaplin and Georgia Hale were having an affair, so that when their finale's lingering kiss was filmed, it was (according to Hale in Unknown Chaplin ) "not acting". By the time the movie was re-issued in 1942, Chaplin was long done with Hale, and he trimmed their final scene to exclude the long kiss.
When shot silent, the film would utilize the entire image area available measuring 1.33:1. When reissued in 1942 with sound the sound strip was overlaid over the left part of the film, and the top and bottom were cropped as well to maintain the 1.37:1 academy ratio resulting in sometimes awkward image composition. This can be seen on the Warner DVD releases of the reissue, while the previous Image entertainment disc was mastered from the full silent aperture negative and does not contain the cropping.
Mack Swain decided to quit, complaining that he couldn't bear such a vigorous role wearing a thick fur winter suit. Chaplin let him leave, but decided to coax him back. Unfortunately, Swain had already shaved and rather than have him wear a fake beard, Chaplin decided to pause production until Swain regrew his beard.