Here's one crazy.
Superman funeral in the third act was modelled after JFK funeral.
JFK presidency and death was said to be like the end of Camelot, by his wife Jackie Kennedy, with the quote coming from a King Arthur play JFK used to love.
BvS already had plenty of parallels to Excalibur and this one another one of them.
Superman dying was like JFK dying, and that marked the end of Camelot. Or its beginning.