The floor in the "I'll Be Hard to Handle" dance was the only wooden floor in all of the Fred Astaire / Ginger Rogers musicals. They both loved working on it, as they could tap and actually make the sounds of the taps. In the other musicals, their taps were dubbed over, as they were too quiet. Their enjoyment is clearly seen, as their giggles at each other are unscripted.
During "I Won't Dance", Ginger Rogers sings to Fred Astaire, "But when you dance, you're charming and you're gentle/ Especially when you do the Continental", referring to the dance in their previous film, The Gay Divorcee (1934). The two then strike a pose from that number while the band plays a riff.
Lucille Ball, who appears uncredited in this film as a fashion model, would later buy RKO, the studio that made this film. At the height of their success during I Love Lucy (1951), she and Desi Arnaz purchased it and renamed it Desilu Studios.
RKO producer Pandro S. Berman insisted that the studio pay whatever it took to buy the rights to Roberta, a huge success on Broadway. The gamble paid off, netting the studio $770,000 and helping RKO post its first annual profit since 1930.
Lucille Ball, who had briefly worked as one of The Goldwyn Girls at Samuel Goldwyn Studios, decided to try out for this film when she heard RKO was looking for girls who had worked as models at Bergdorf Goodman in New York City. She had not actually been employed by Bergdorf, but had participated in a fashion show a promoter had put on there, so she applied and got the job.