This was MGM's first full-length feature in three-strip Technicolor. As such, viewers can see the constant shift in quality between scenes, chiefly in the makeup, which often appears garish and overstated. One short year later, the process would be perfected in time for The Wizard of Oz (1939) and Gone With the Wind (1939).
This is MGM's first film to feature a different lion roaring in the logo, by the name of Tanner. This lion appeared at the beginning of MGM's Technicolor feature films and cartoons.
The large set that Nelson Eddy and Jeanette MacDonald perform the title song on is actually a piece of the dismantled set from the "Pretty Girl Is Like a Melody" number from The Great Ziegfeld (1936). This set piece was later used in Two Girls on Broadway (1940) and Ziegfeld Girl (1941) among other films.
One of the Times Square marquees is advertising Idiot's Delight (1939) starring Alfred Lunt and Lynn Fontanne which MGM had just purchased the film rights for.
The lavish musical number that was staged for the title song, re-uses the enormous, reticulated descending silk curtain that was originally created for the 'Pretty Girl Is Like A Melody' number in "The Great Ziegfeld" in 1936. This remarkable, custom made artifact was also later used in "Babes on Broadway" (closing number) and "Lady be Good" (closing number.