The real life names of the competing railroads were Union Pacific and Southern Pacific. Though both railroads were major competitors in the state of California, they would finally merge in 1996 to become the largest railroad in the western half of the United States.
The title and premise are a parody of the Union Pacific Railroad and Cecil B. DeMille's Paramount feature Pacific Express (1939).
This is the final appearance Wimpy in a Fleisher Studios Popeye theatrical cartoon. Wimpy wouldn't appear in another theatrical cartoon for 10 years until Popeye Makes a Movie (1950) from Paramount's Famous Studios.
As the short opens, the song "We're All Together Now", from the Fleischer Studios color feature Les voyages de Gulliver (1939), can be heard playing.
As with most of Paramount's Famous Studios films of this era, the background images are carefully rendered with attention to the smallest detail.