dude in their concert that I worked 3 days of they had floating helium spheres with LED lights in them.
we were told to keep all doors shut to keep the draft away so the things wouldn't just fly off or randomly fly to the audience which everyone knew would result in a brawl to decide to who get to keep them.
Also there was a space ship balloon full of helium with air plane lights attached (it just looked like black plane frankly). A full SIA escort had to be deployed to protect the stage crew so they could safely extract it from the arena as it landed amongst the crowd.
Also first night giant balloons (like the size to fit 5 people) full of confetti was thrown into the arena like a beach ball party and needed to be popped before the show could continue.