Trivia: When Richard the Buffalo accidentally steps on Ray the Snail, you can hear the Wilhelm scream.
Trivia: The way Ash stops playing her guitar and looks at the audience resembles the way Marty does in Back to the Future. Other references: When Buster Moon is trying to connect the wires but they won't reach, this happens in BTTF when Doc is trying to reconnect the wire to the top of the clock tower. The moon theatre even resembles the theatre in the Hill Valley town square (the one near the car park in 1985). The theatre in Sing even has a clock on it.
Answer: It would have to do with paying royalties to the artists if the songs were included on the soundtrack album. The artists would be paid a one-time flat fee for their songs to be used in the movies or the trailers, but for albums being sold would mean some of the profits would have go to the artists. The movie studio can make just as much on the soundtrack album without certain songs being included. Regarding the title, it may be the artist wanted it changed for some reason, or the filmmakers felt it didn't fit in.
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