In 1995, actress Fiona Shaw (a.k.a. Aunt Petunia Dursley in the Henry Potter flicks and the witch Marnie in Season 4 of True Blood) played the role of Richard II in a National Theater production, which was televised by the BBC2 in 1997 (source).
In the Reduced Shakespeare Company's "Tweeting Shakespeare" project, Richard II is summarized as follows: "Absolute power corrupts two in the bush" (source).
In 1601, the Earl of Essex led a rebellion against Shakespeare's monarch, Queen Elizabeth I. The day before the rebellion, Essex's friends hired Shakespeare's theater company to perform Richard II at the Globe Theater. Even though the play was about four years old, the rebels hoped it would get people riled up about revolting against the current monarch. The revolt failed, and some of the actors had to testify in court during Essex's trial. What was Queen Elizabeth I's reaction to this play? Apparently, she snapped, "I am Richard II. Know ye not that?" (source: Chambers, E. K. William Shakespeare: A Study of Facts and Problems. 2 vols. Oxford: Clarendon Press, 1930).
The deposition scene (where Richard is forced to give up his crown) was censored from printed editions of the play during Queen Elizabeth I's reign. Apparently Elizabeth didn't want readers getting any ideas about bumping her off the throne (source: Shapiro, James. A Year in the Life of William Shakespeare: 1599, 2005).
Richard II is the only Shakespeare play written entirely in verse, or poetry. (See "Writing Style" for more on this.)
Even though Shakespeare decided to make her an adult in the play, Richard's queen, Isabelle of France, was actually just a kid. She wasn't quite 7 when he married her and only 11 when he died (source).
King Henry's snatching of the throne led to his reign being plagued with rebellions (source). (Psst. Shakespeare tells us all about it in the sequel, Henry IV Part 1.)
During Episode 8, Season 6 of The Simpsons ("Lisa on Ice"), Ralphie Wiggum says, "Me fail English? That's unpossible." (Check it out here.) About 400 years earlier, the word "unpossible" appeared in Richard II, when Bushy says, "For us to levy power / Proportionable to the enemy / Is all unpossible" (2.2.6).