Henry IV Part 1 makes several self-conscious references to the workings of Elizabethan theater. Most notably, the wild impromptu skit at the Boar's Head tavern presents a "play-within-a-play" that offers an opportunity for Shakespeare to explore the relationship between rebellion and the stage. Because it's a space where Prince Hal can practice being "king," the tavern is also a kind of training ground or important rehearsal space for the young man who will inherit the throne. Frequent play-acting and character impersonation throughout Henry IV Part 1 give voice to the notion that "kingship" is just another "role" to be played. The play's concern with meta-theatricality aligns it with other important works, including Hamlet, The Taming of the Shrew, and A Midsummer Night's Dream.
By portraying a play-within-a-play at the Boar's Head Tavern, Shakespeare highlights the relationship between the theater and rebellion.
Henry IV Part 1 explores the relationship between theatricality and leadership – ultimately, the play suggests that kingship is merely a "role" that can be "played" by anyone with acting skills and the right "costume."