The mouse who says "Pussycats is da cwaziest peoples" is spoofing radio comedian Lew Lehr, whose catchphrase was "Monkeys is da cwaziest peoples."
This marks the first time the cat is named Sylvester. The cat was previously unnamed in shorts but in O Canarinho (1947) was named "Thomas".
The cat Sylvester sees is riding in a tumbrel, which is a wheeled cart used to transport victims to the guillotine during the French Revolution.