A WW2 reference is shown at the end of this short, to the B19 bomber. Such patriotic messages were common in wartime, even in cartoons and magazine ads.
The earlier Bugs appears here, with his more pronounced, wisecracking demeanor, NYC-esque accent, and pinker ears. But he still manages to kiss his enemy, something he'd do throughout his career---along with breaking the fourth wall.
Elmer breaks the fourth wall several times in this short.
The paranormal was a subject of interest at the time, both in films and real life. Wartime research included the use of hypnosis in many situations.
Vitaphone production reel #723A.