What movie features male musicians disguised as women in an all-female jazz band after witnessing a mob hit?

The movie is Some Like It Hot.

This classic comedy features a plot centered around two male musicians who are forced to go on the run after witnessing a mob hit.

Plot Summary Based on References

Based on the provided references and the well-known plot of the film:

Setting: The story kicks off in Chicago during the winter of 1929.
Protagonists: Two Chicago musicians, Joe and Jerry, become unintended witnesses to a violent mob crime.
The Escape: To escape the gangsters pursuing them, they decide to flee the state.
The Disguise: Their ingenious (and complicated) plan involves joining an all-female band. To blend in, Joe and Jerry disguise themselves as women.
Further Complications: As the plot unfolds, their disguises lead to numerous humorous complications, including romantic entanglements and the continued threat from the mob.

The premise of male musicians joining an "only girls in jazz" band while in disguise is the core concept of this iconic film.

Here are some key elements highlighted by the plot:

This setup provides the foundation for the film's comedic situations and memorable performances.