Carefree is the shortest of the Astaire-Rogers films, featuring only four musical numbers. Carefree is often remembered as the film in which Astaire and Rogers shared a long on-screen kiss at the conclusion of their dance to "I Used to Be Color Blind," all previous kisses having been either quick pecks or simply implied.
Astaire didn't like "mushy love scenes," and preferred that lovemaking between him and Rogers be confined to their dances. Because rumors sprang up that Astaire's wife wouldn't let him kiss onscreen, or that Rogers and Astaire didn't like each other, Astaire agreed to the long kiss at the end of "I Used to Be Color Blind", "to make up for all the kisses I had not given Ginger for all those years."
I thought I'd found the "Big Kiss" c/o obscureclassics but the link has been disabled due to copyright issues. Unable to find videoclip of the extended kiss; but here are a couple of Astaire-Roger pecks...
Swing Time (1936) Fred Astaire and Ginger Rogers. Directed by George Stevens
This scene from The Story of Vernon and Irene Castle includes the song "Only When You're In My Arms", Vernon's proposal of marriage and a very rare kiss involving Fred Astaire and Ginger Rogers.