The Chilkoot Pass, where Elizabeth Bryant's husband was killed, is a high mountain pass through the Boundary Ranges of the Coast Mountains in Alaska and British Columbia, Canada and is the highest point along the Chilkoot Trail. During the Klondike/Yukon Gold Rush of the 1890s, it was the most popular route used by prospectors to get through the mountains.
This episode takes place in June 1899, which is why it was still light out at 1am when Murdoch was in the mining camp.
A character seems to be reading a paperback book near the beginning of this episode. While paperbacks were not available until 1935, the man is actually reading a "dime novel," titled Steam Man of the Prairies, which was first published in 1868.
First appearance of Georgina Reilly who plays Dr. Emily Grace.