"Bohemian Rhapsody" has foreign words like "Bismillah!" and "Scaramouche" doing the Fandango. Yet, if Beelzebub was sending demons after me, I'd be using Middle Eastern prayers too.
If you list the Queen album tracks in chronological release order, '39 is the 39th.
Queen II and A Day at the Races are sequenced by songwriters: in the days of vinyl records, Queen II had a white side chiefly written by Brian May (one song by Roger Taylor) and a black side completely written by Freddie Mercury; A Day at the Races alternates songwriters: May-Mercury-May-Mercury-Deacon on side A, and Mercury-May-Mercury-Taylor-May on side B.
Freddie Mercury came up with the initial idea of "Was It All Worth It", and then the rest of the band completed the lyrics with him. It makes sense: they begin in singular ('what is there left for ME to do in this life?...') and then they turn plural ('we bought a drum kit...').
This depends entirely on how much you read into the line about being left alone with Fanny the naughty nanny of Queen's "Fat Bottomed Girls", but if read a certain way it becomes a statement that Fanny was in fact a child sexual abuser.
Or that she was fooling around/having sex with people while she was supposed to be working and the kid found out.
The guitarist for Queen, Brian May, wrote the song '39. In a DVD commentary, he mentioned that it's based on the idea that the faster you go, the more time slows down. So the astronauts came back to Earth after a year in their time to find a century has passed planet-side. Thus, the line "Your mother's eyes, from your eyes, cry to me." becomes fridge... sorrow?
What, you didn't get that on first hearing?
It's speculated that "I'm Going Slightly Mad" from Innuendo is about Freddie's AIDS-aggravated dementia. Black Humour, perhaps, but chilling in retrospect.
The song "Good Company" by Brian May is essentially about a man who neglects all his relationships and is now old, living alone, and essentially talking to himself. Fridge depression?
Great King Rat died when he was 44; Freddie died when he was 45.
"All Dead All Dead" was written by Brian May about the death of his cat when he was a child, which he reportedly never quite got over. The bond between a kid and his pet is often extremely close, but more so in the case of an only child living in 1950's London and having very few friends. Experiences like that one may have influenced his animal activism as an adult.