Mae Questel did both voices for Olive Oyl and Popeye. Jack Mercer had just enlisted for military duty in WWII and wasn't available to do Popeye's voice.
The opening signs are a send up of the popular Burma Shave advertising billboards of the era.
One of the few times Popeye is seen with a beard.
The war in the Pacific was bringing plotlines of tropical island idyll to the silver screen, as shown here.
It's presumed Olive is swimming au naturel (a la Hedy Lamar), but censorship wouldn't allow more than a naughty inference.