Western Onion is a pun on Western Union. Telegrams were still a means of getting important news to people in the years before long distance telephone calls became commonplace.
The intercom voice speaks in Pig Latin, which was popular at the time.
Although modern viewers might not recognize it, the end sequence was a nod to the Junior, the Mean Widdle Kid radio character, popularized by comedian Red Skelton. Cinema audiences, where cartoons were screened in the days before TV, would have appreciated the humor back then.
Made during an era when mad scientist horror movies, floor console radios, and big band music (and radio programs) were popular.
The story has a secondary plot that spoofs Robert Louis Stevenson's novella "The Strange Case of Dr. Jekyll and Mr. Hyde."