Beckett investigates a murder in an alleyway while Castle, stuck at home with a broken leg, investigates a murder across the street. It is the 100th episode of the series.
- April Fools' Plot: In a meta sense. This episode premiered on April 1, 2013, foreshadowing that the murder witnessed by Castle was staged all along. Even Captain Gates is in on the plot.
- Batter Up!: The victim was killed by having her head knocked in with a baseball bat.
- Creator Cameo: Andrew Marlow and Terri Edda Miller appear as a couple across the way from Castle. Another shout-out to Hitchcock.
- A Deadly Affair: The killer was the victim's husband alongside his mistress.
- Eating the Eye Candy: Alexis enjoys watching the guy across the street taking his clothes off (Castle doesn't enjoy that she enjoys it). Subverted when he then puts on a respirator...
- Friendly Scheming: The supposed murder witnessed by Castle turned out to be a pretext for Beckett's birthday party.
- Gambit Roulette: There's no way in hell Beckett's plan could really have worked, but it's so awesome and sweet that it doesn't matter.
- Gaslighting: As a birthday present for the broken-kneed Castle, Beckett hires actors to fake a murder and gets the rest of the 12th to play along with pretending it's all in his head as he goes Rear Window on painkillers. At The Reveal, Castle is delighted.
- Manly Tears: Castle is so happy that he cries when he learns that all of his friends pranked him with a fake murder to keep him from getting bored while was down with a broken knee.
- Oh, Crap!: At first Castle has fun watching the lovers quarrel and break up, but then the guy picks up a knife...
- Pass the Popcorn: Castle and Alexis share popcorn once he gets her to join him in spying on the guy across the street.
- "Rear Window" Homage: The film itself gets name-dropped, as does its star, Jimmy Stewart.
- The Reveal: The murder across the street from Castle's apartment was all a scam cooked up by Beckett as a birthday present for Castle.
- Shout-Out: In addition to Rear Window, Castle watches a red-head get in some shenanigans cheating on her husband and says she's got some splaining to do.
- Un-Installment: Suggested; Castle and Beckett observe that they have solved a hundred cases together, but with the two-parters (which were single cases) to take into account there must have been a few cases they solved that haven't been part of the show.
