The title is a pun on that of the movie feature "Unexpected Guest" (1947).
The full score for this cartoon can be heard on the album "The Carl Stalling Project Vol. 2: More Music from Warner Bros. Cartoons 1939-1957". The score is also heard on the fourth Looney Tunes Golden Collection DVD set as a music-only audio track.
Although the background artwork had become more abstract and less formal (as befits the era of mid century modern design), some typically suburban necessities are still shown, including a backyard trash incinerator. At the time, burning household rubbish was not considered unusual.
The mouse sounds a wee bit like Sylvester's other nemesis, Tweety. Mel Blanc truly had a multitude of voice characterizations.
Sylvester's owners live in a mid century ranch style home, complete with a garage for the big, shiny muscle cars that were popular at the time.