The wreckage from the train crashing into the river is still there today, decades later! The wreckage is located at N 47°19.785 W 123° 38.595, along the Wynoochee River, near the Olympic National Forest in Washington State.
The bridge that was destroyed in the film was built by the Simpson Timber company in 1939, but had been abandoned for nearly a decade. Rails had to be reinstalled on the bridge to allow the steam locomotive and train cars to roll onto it. Explosives were used to increase the dramatic effect of the bridge's collapse. After filming, it was discovered the gorge of the Wynoochee River was too deep to remove the train, so the cars were cut in half and they and the locomotive were left in place. The filming of the bridge fire and collapse took place on October 7, 1960.
Extras for the role of running wildly up the street from the fire were offered $10.00 per day.
The razing of a Vernonia planning mill owned by the International Paper Company was filmed as part of the shoot, and some forest fire footage was captured outside Baker, OR.
The film was shot in Vernonia, Oregon and Wynoochee River, Washington, featuring footage from two real forest fires in Oregon and California, then cut into the picture. Filmmakers also planned to burn down an estimated 40 acres of "valueless" forest near Shelton, and other fire footage was said to be captured in Truckee, CA. The fictional fire was reportedly "based on the Hinckley, Minn. disaster of 1894. Then director Andrew L. Stone used the entire town of Veronica for the scenes of escaping citizens in freight cars for authenticity.