The gold spike used at the ceremony to mark the end of the construction was the same spike used in the May 10, 1869 event, on loan from Stanford University.
In order to operate the number of trains required by the production, Paramount had to get a regulation railroad operating license from the Interstate Commerce Commission.
The world premiere in Omaha, NE, was a three-day celebration that drew 250,000 people, doubling the population of the city and requiring the National Guard to help keep order. The special train en route from Hollywood to Omaha, carrying Cecil B. DeMille and stars Barbara Stanwyck and Joel McCrea, took three days and made stops along the way, drawing large crowds. The film was shown in three theaters simultaneously; President Franklin D. Roosevelt was reported to have started the premiere proceedings by pressing a button in Washington, DC, which opened the civic auditorium. An ad stated that the premiere, which involved parades, radio broadcasts and a banquet, was the biggest in motion picture history. An antique train continued on a 15-day coast-to-coast promotional tour, stopping at 30 cities around the country.
According to Lucius Beebe's book "Union Pacific" the gold spike was not driven in. Since a spike made from gold would be much too soft to drive into a railroad tie, the spike was lowered into a hole drilled in a specially prepared tie. This was done both in reality and for the movie. Following the ceremony, the spike was pulled out (by hand) and a new tie was put down and an iron spike was inserted.
According to a news item in "The Hollywood Reporter", Cecil B. DeMille directed much of the film from a stretcher, because of an operation he had months earlier. However, studio records indicate DeMille collapsed from the strain of directing three units simultaneously, and used a stretcher for about two weeks.