William, The Man in Black, is listening to "Ring of Fire" by Johnny Cash, who was known as the Man in Black.
In November 2022 HBO announced the cancellation of the series. Creators and directors were hoping for a season 5.
The title "Que Será, Será" (Spanish) means [whatever] will be, will be.
Que será, será is the name of a song by Doris Day and Frank De Vol.
The character that gets "axed" in the head in the opening scene is Rubus, played by Steven Ogg. He appeared in S1.1, 1.3, 1.10 and S2.3.