Sylvester actually felled a badminton shuttlecock, also known as a birdie.
The background details in this short have become less detailed and more streamlined, as design moved into the modern 60's.
Radio controlled model airplanes (and boats), shown here, were very popular amusements in the 50's and 60's for kids and adults alike.
Junior's feathers blue friend is named Spike. Spike was also the name of several animated bulldog characters at the time.