When construction workers find the body of an infamous New York mobster who disappeared in the the '70s, Beckett and Castle try to solve this three decade-old mob hit. Their investigation is complicated when it transpires that their key lead is a delusional ex-gangster who's mentally still believes he's living in the '70s.
- The '70s: The entire theme of the episode. With Beckett and Castle redecorating the morgue and the precinct to look like the '70s, and everyone dressing in '70s clothing in an attempt to keep Harold Leone mentally stable long enough for him to give them the information they need to catch Vince's killer.
- The Alleged Car: The 1970s cruiser they dig up is clean, but it barely runs.
- Armored Closet Gay: Harold Leone relentlessly makes inappropriate comments about the women around him but it is revealed that he and Vince Bianchi were in love back in the '70s despite both of them trying really hard not to be. It got to the point that Harold insisted Vince find a girl and get married to avoid suspicion. And it's Harold's denial over Vince's death that causes him to become mentally stuck in the seventies.
- Awful Wedded Life: Frank's wife is very bitter about "only" living in a 4000-square foot apartment instead of having the penthouse since the family pushed him out and gave him "crumbs".
- Bad "Bad Acting": Martha writes scripts for everyone in the precinct, but they're not actors and have no time to practice, so everyone is struggling with their lines and her writing.
- Brick Joke: Esposito and Ryan dress up as Snookie and Ray, the guys from the documentary Esposito found.
- Car Hood Sliding: Esposito tries one of these when he, Ryan, and Harold arrive at Glitterati, as he saw Snookie do so in the documentary he saw. However, while Snookie pulled if off fine, Esposito just slides and lands on his ass.
- Constructive Body Disposal: The reason the victim - Vince Bianchi - has been missing since the '70s is because his body was hidden under concrete which was only recently disturbed by new construction.
- Dance Party Ending: The episode ends with the main cast and Harold going out to a disco club together.
- Death by Woman Scorned: Marie Carcano believed Vince was going to propose to her to cement the union between the Carcano and Bianchi crime families. But after he took her out for a romantic night, he couldn't go through with it. She responded by shooting him In the Back as he walked away... and then in the face! To avoid a mob war, her brother covered it up.
- Disco Dan: Harold Leone has a mental condition that makes him convinced it's still the '70s, and anything that breaks that bubble causes him to become confused and frightened.
- Dirty Old Man: Harold makes plenty of comments whenever he sees a woman dressed in hot clothes. When it's revealed he's actually gay, we find out this is just a front he puts on.
- Distracted by the Sexy: During the disco club ending, Esposito comments he wouldn't like to live in the '70s until he sees Lanie is a very attractive dress.
- Earn Your Happy Ending: Harold spent decades trapped in his own mind after the love of his life was murdered, but he gets to learn the truth about how Vince died and the depth of their romance.
- Gayngster: Harold Leone and Vince Bianchi.
- Irony: Castle says they can get away with redecorating the precinct to look out of the '70s because Captain Gates is at an anti-terror conference. When he and Beckett are getting chewed out by Gates after she comes back early and sees what the hell is going on, she explains the conference was cancelled due to a bomb threat.
- Jive Turkey: Martha's writing is full of this.
- Obfuscating Disability: Harold had actually overcome his pathological grief after the attempt on his life, but kept up the façade so that the cops would lead him to Frank Russo, the man he believed responsible for Vince's death.
- Retired Monster: A lot of the gangsters that Beckett and Castle meet who were active in the '70s and are still alive have either gone legit or been forced out of The Mafia by virile, younger competitors. Most have also ended up a Henpecked Husband to a Spicy Latina wife.
- Truth in Television: Harold and Vince loved the disco, frequenting The Glitterati and dancing their hearts out. Discos were huge gay scenes, because the dance floors were chaotic and unstructured with their change to a four-to-the-floor music style that let people dance near each other without having to openly partner up. This meant they could be with their partners in public without risking arrest and assault by the police for being openly gay.
