Released at a time when science fiction and evil inventors were a common theme in entertainment. The splendid attention to detail in the lab here gives a slightly macabre feel to the otherwise humorous action.
The Production Code at the time required a wedding, even for mice. The mice here take their vows in a novel way, by playing a horn.
Dr. I.M Nutts is a play on "I am nuts", or "I'm nuts".
The mouse symphony here predates Disney's Fantasia by two years, but several studios had been doing shorts that mimicked the Disney series Silly Symphonies.
Both Johnny Mouse and the evil cat break the fourth wall, an early example of what would become a WB cartoon standard.