When the "inspector squirrel" stamps the acorns as they roll by him, the image that is left on the acorns is Hebrew for the word "KOSHER."
Made for cinema audiences, so adult humor (slot machines, weight reduction belts) were added for adult viewers.
A not so subtle moral lesson about the evils of illegal gambling. Post-prohibition, the gaming 'industry' (and its shady underworld connections) were a new public enemy.
It would make sense that squirrels would save their nuts at the First 'Nut'ional Bank - an obvious play on First National Bank.
The title song parodies the 1936 song, "(Who Is My Baby Gonna Love All Winter) Now That Summer Is Gone" by Mildred Bailey.