A plain backdrop was used for closeups of the riders in the tandem horse race, which made it obvious that the riders weren't really on the horses.
When the band plays "You Lovable You" in a crowded corner on the dance floor, there appears to be a stage to the left (band's right) that would be more accommodating.
Jackie takes a drumstick and starts beating out a rhythm on the cymbal to start "Separate the Men from the Boys", then passes the drumstick to drummer as she proceeds to sing. Three hits on the cymbal are heard while they're passing the stick.