Well, I am lost. Elderberry wine? Kamizake?
Yes, elderberry wine is the period (intended period of the movie) equivalent to MD 20/20. Cheap, stinky wine. If one smelt of elderberries it was a sure sign of a desperate drunk (or so I’ve read).
You can use your favorite search engine with the search term “what does your mother was a hamster and your father smelt of elderberries mean” (sans quotes) and get a fair number of hits that have similar answers to the question.
To an extent; all art is what one reads into it or interprets it as - even British performing art...