Opera is live and because it's live anything can happen. That's half the fun of any live performance. If a production is too elaborate, too detailed, too busy, there's no way to discern what's planned and what's funny. Excess leaves no room for the audience to bring its own feelings into the experience.
There have been singers who have died on stage. There have been performers who have gotten sick or been injured on stage. It is a live art form with real people and anything is possible.
Personally, I want to watch real people on the stage. Opera requires singers with stamina. It is a very physical art form. I want to see and hear powerhouse performers. There's a sense of security. Full-bodied performers suit me fine. Opera singers should not be straws.
With live theater there will be bloopers, fabulous bloopers. The who, what or where doesn't matter. Bloopers stand on their own merit. They need no captions, only an understanding of the opera. Good bloopers don't happen often, maybe once every three years. They may be part of a planned staging or they may be a glitch, but there's no way around it, a blooper is one of the joys of opera.