One of the most famous (and terrifying) examples happened during a massive outdoor tech product launch in the early 2000s. The "Invisible" Piano

They ran the audio through the massive, professional-grade sound system already in place.

The event was a high-stakes gala featuring a world-renowned pianist. The stage was set on a custom-built platform over a reflecting pool. It looked stunning—until two hours before doors opened, when the arrived.

The pianist agreed. The audience was none the wiser; they saw a gorgeous grand piano over the water and heard world-class audio. The event was a triumph, and the stage held firm.

They gutted a high-quality electric keyboard and mounted it inside the shell.

In events, the audience only sees the "swan" gliding across the water. They don't need to see the "legs" (the managers) paddling like crazy underneath to keep it afloat.

They sourced a (a stage prop used in plays).