Basic Trope: Dancers appear out of nowhere to help with a musical number.
Straight: Clare is facing an armed squad blocking a bridge. Since this is a musical, she summons a group of dancers to help her dance fight against all of them.
Exaggerated: Clare summons so many dancers that they collapse the bridge with their combined weight.
Downplayed: There a lots of mirrors and reflective surfaces nearby, along with one or two people who gamely help Clare with basic choreography, which just so happen to make it look like Clare is really dancing with tons of people.
Justified: Clare knew about the blockade, and used herself as a distraction so her friends can sneak up on the soldiers and further disorient them with dance synchronized fighting.
Inverted: Clare is walking to the bridge with her musical theater troupe, who run away in fear once they see the soldiers.
Subverted: Clare starts singing, dancing, and once she reaches the chorus... no one sings it. She's all alone.
Double Subverted: Because they were waiting for a Big Damn Heroes entrance, and after a beat swoop in singing.
Parodied: Clare takes out a bottle marked "Acme Dehydrated Dancers" and rehydrates them.
Zig Zagged: Clare makes angels appear to sing alongside her, except they were just a figment of her imagination, until they came to life! But it turns out it was a Dream Within a Dream, and Clare isn't even singing out loud.
Averted: Whenever someone sings and dances, they do so alone.
Enforced: It's a musical.
Lampshaded: "You know, I wonder where all those backup dancers go after a song is done? Do you think they just go for coffee or cash a check or something?"
Invoked: Clare organizes her friends and coworkers into a passable backup dancer group, and gives them Supermanlike spandex costumes to wear under their clothes so they can beat their rivals.
Exploited: The bridge guards know that Clare may come in to dance battle, so they rearrange the layout of the bridge to make it both too narrow and not carry music well, thus limiting any benefits number or dance fighting would have.
Defied: Clare shoos away the backup dancers so she can do a solo song.
Discussed: "You soldiers think you outnumber me? All I have to do is sing a few words and I'll have a platoon backing me up!"
Conversed: "If everyone on this show can make backup dancers appear when they sing, no matter where they are, how can they not feel like they're Being Watched all of the time?"
There is an agency you can contract that trains ninja-dancers to follow you around, and sing and dance along side you at a moments notice.
No one sings. Ever, Not even humming alone, since doing so may cause an impromptu musical number at the most annoying time.
Reconstructed: The lead characters have to spend considerable time training alongside their backup dancers, or to literally summon them.