Dream sequences and the freedom they give choreographers
Launch library · evergreen read

A dream sequence hands choreographers a rare gift: permission to abandon realism entirely. Because the audience already understands they are watching a character's imagination rather than literal events, costume, setting and movement can shift illogically from one moment to the next without breaking the story's internal rules.
This freedom often shows up in scale and fantasy elements that would look out of place elsewhere in the film, elaborate sets built purely for the sequence, sudden costume transformations, or dance styles quite different from anything else the character performs. The number can borrow visual ideas from anywhere, since a dream justifies almost any imagery.
Composers frequently support this freedom with a more expansive musical arrangement too, layering sounds and instrumental flourishes that would feel excessive in a grounded, everyday scene but suit a heightened, imagined world perfectly. The song effectively becomes a small film tucked inside the larger one.
Because dream sequences are so clearly bracketed as unreal from the outset, they tend to age rather differently from the rest of a picture, remembered fondly as pure spectacle long after the surrounding plot details have faded from memory entirely, kept alive purely by their imagery.