Must be a pretty serious scenic glitch, because I've heard of this happening at a performance about a week before I saw it as well.
Candydog: Ursula is weirdly attached to this odd bubble-like thing for most of the show. It's quite difficult to describe, but it is a black bubble, with a "convertible" cover, so as to hide whosoever goes inside. Sometimes, it functions just as a bubble, but during Ursula's first song, "Good Times", there are some of her tentacles protruding out of it. Which creates an odd effect when halfway through the number she steps away from it, leaving some of her tentacles behind...
"Are you sorry for civilization? I am sorry for it too." ~Coast of Utopia: Shipwreck