My family hails from the Camas Prairie, and even though I personally was not around at the time, they were and remember watching the filming, including the wreck scene. Film production was plagued by low snowfall that year, and in some cases snow was hauled in for scenes. Most of the filming was indeed done on the Camas Prairie Railroad, and the Myrtle set was built on the opposite side of the river from the real Myrtle, ID. I was told some of the snowier train scenes were actually filmed in Montana though. Great movie! It is in my collection!