Production was halted because of the June 7, 1937 death of William Powell's fiancée Jean Harlow. Powell later described finishing the movie as "very difficult under the circumstances". Myrna Loy, a good friend of Harlow's, disliked the film because of her death, stating in her autobiography it was "the scapegoat for concurrent despair".
The Oscar statuette at the end was a joke the audience at the time would have understood. At the 1937 Academy Awards, William Powell had been nominated for Best Actor for My Man Godfrey (1936), but ended up losing to Paul Muni for The Story of Louis Pasteur (1936); Powell had also starred in The Great Ziegfeld (1936), which was awarded that year's Best Picture honor. Many felt Powell had been robbed of an Oscar at the March 1937 ceremony, which was held shortly before that final scene was filmed. "Double Wedding" was released in the fall of 1937, so the reference wouldn't have been lost on the audience.
After Spike shoots the gong in Charlie's trailer with a BB gun, the bartender hands him a cigar. This is a reference to the fact that many carnival games at carnivals and fairs originally gave cigars as prizes, including at shooting gallery games. It's the source of the saying "Close, but no cigar."
The film resulted in large part from the commercial failure of Parnell (1937). That film had featured Myrna Loy and Clark Gable, a pairing the studio wanted to cultivate, but audiences had a cool response to the product. MGM wanted Loy to rebound from the failure with what they knew was a bankable formula -pairing her with William Powell. The studio's instincts were correct, and this film was a commercial success. Incidentally, the Parnell flop did not permanently sour MGM's attempt to pair Gable and Loy; the two co-starred twice the following year in Test Pilot (1938) and Too Hot to Handle (1938).