Alternate Character Interpretation: Some have speculated that the frog is deliberately not singing for the man in order to get him in trouble. Some even speculated that the man was hallucinating the frog dancing, but this has obviously been Jossed. The ending to "Another Froggy Evening" suggests that the frog will sing if properly asked. And that it isn't croaking, it's saying: "Do you want another song ?" in martian language. Which Marvin the Martian ends up being the only one to understand.
Newer Than They Think: "Michigan Rag". Unlike the rest of the songs in One Froggy Evening, this wasn't old, but created specifically for the short by Chuck Jones, Mike Maltese, and composer Milt Franklyn.
"Weird Al" Effect: Most of the songs that appear in the short are only known to audiences today for their appearance in it. Furthermore, if one of the songs shows up in a piece of media today, it's probably going to be as a parody of this cartoon (see Spaceballs for one example).
The Woobie: Admit it, you felt bad for that guy at some point or another.