Continuity mistake: Before the final torpedo, the projector lenses are out. After the explosion, the Batboat is gone, and the projector is again concealed. Batman didn't have time to put the cover on.
Continuity mistake: As the Batcopter approaches the yacht, switching between the aerial view and inside the cabin, Batman is seen both standing outside ready to descend the ladder, and piloting. (00:06:25)
Answer: The Riddler doesn't sing at all. He yells to the henchmen on board, "Prepare to repell boarders!" He does it in a almost musical way, true, but there's no song.
CCARNI ★