To simulate the emergency braking of a speeding train, Desilu Productions was not content to use a standard method of jolting the camera and having the actors move in reaction to a non-existent jolt. Desilu wanted absolute realism, so the set containing the train's curtained berths and a hallway leading to the door with the emergency brake next to it was built in a box frame that contained a spring mechanism that was in turn triggered by the emergency brake itself. When Lucille Ball pulled the handle of the brake, it released a metal spring that caused the entire set to lurch forward in a movement that often brought the actors to their knees; thereby accurately simulating an emergency braking of a train's movement. This is demonstrated in the special features section of the DVD.
J. Edgar Hoover, who is referenced in the episode, wrote a fan letter to Lucy following the episode's airing.
The Union Pacific Railroad put up money for set construction on this episode in exchange for the advertisement of their passenger trains. By 1956 passenger train customers and revenue were dwindling and any opportunity for publicity was welcomed by the railroad.
A scene that was in the episode when it originally aired but then cut in all subsequent airings of it has been restored for the series DVD release. The scene in question happens before the train departs Los Angeles. The Mertzes pass by the Ricardos' compartment to tell them they're heading to the dining car for something to eat. We then see the Mertzes being ushered to the upper level of the train to eat in the diner's open dome section. This scene was most likely cut do the fact that, due to light moving along the ceiling when the Mertzes arrive upstairs, it seems like the train was moving, whereas the next scene establishes that the train has not yet departed Los Angeles's Union Station.