A double-barreled gunboat cannon for a WWII-themed HMS Pinafore performed by UMGASS.
This cannon was on stage the entire show and moved only in the last seconds of the finale. The audience seemed to like the cannon, despite its limited part.

The gun rotated from aiming upstage right to stage right. One barrel had a Union Jack that popped out by pulling on a rope, and the other barrel had a home-made air cannon that fired confetti.