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: I think he escaped from the bear with his girlfriend, sped off very fast and the bears fell off the car.
You haven't read the question. Before it cuts to Meena's performance, the lead bear popped up from behind the car and presumably kidnapped them.