The film portrays Buck as a Leonberger. Leonbergers were never used as sled dogs. This is also contrary to his description in the original novel, in which he is a crossbreed that resembles a large wolf.
Sol-leks appears to be a black-and-white Siberian Husky with sectoral heterochromia, but the film is set in Alaska in the 1890s, and Siberian Huskies were not imported to Alaska until 1908. Prior to this time, Alaskan Malamutes were the most common breed of sled dog in Alaska (and almost the only sled dogs used in the Gold Rush). Furthermore, Siberian Huskies did not develop their blue eyes until around the 1940s.
The film is apparently set in the summer of 1891, but the Klondike Gold Rush took place between 1896 and 1899 (the book was set in 1897).