Day 3: 11:00 P.M.-12:00 A.M. - S3-E11
Trivia: When the CTU personnel are in a meeting and Adam brings a picture of Nina onto the big screen, the name next to the picture is Sarah Berkeley, which is Sarah Clarke's married name. Clarke has been married to Xander Berkeley since 2002.
Trivia: At around 5 mins 11 seconds into the episode, Vincent Nigel-Murrey and Dr. Saroyan are discussing the bones on the forensic platform. In the background of a shot of Vincent, the x-ray on the screen is of Homer Simpson's head in the middle of the screen, instead of a real human skull.
Trivia: Castle's Halloween costume is of Malcolm Reynolds, played by Nathan Fillion in the short-lived TV show "Firefly." Alexis asks him: "Didn't you wear that like five years ago?" Serenity, the film based on Firefly, was released 5 years before this episode aired.
Man of Science, Man of Faith - S2-E1
Trivia: During the opening scene, when the camera cuts to the cabinet of drugs (shortly before the explosion heard in the distance), all the bottles of drugs have 'the numbers' on them - '4, 8, 15, 16, 23, 42'. Maybe obvious to some but worth looking out for. (00:02:20)
Trivia: The man that Ms. Gordon, Parole Officer mistakes for Magnum, and that later he admits "sort of look alike" is Tom Lupo, a stunt coordinator and most importantly Tom Selleck's stunt double for this very series. (00:22:35)
Trivia: Author Tess Gerritsen, creator of the series of novels upon which the TV series is based, appears as an author at the mystery writer convention.
Trivia: In this episode the director, Bryan Singer, makes a cameo as the director of the sports documentary Hank Wiggen is starring in.
Trivia: Columbo's first name is never mentioned throughout the series. However in a few episodes, such as "Dead Weight", "A Matter of Honor" and "Death Hits the Jackpot" he flashes his badge and the name "Frank" can clearly be seen.
The Red Sea Sharks: Part 1 - S3-E1
Trivia: The Emir's hideout is strongly based on the Al-Khazneh temple at Petra. (00:19:25)
Trivia: The Observer appears in the hospital. The agents walk pass him on their way to see the dead man-baby. (00:09:20)
Trivia: The fight between Satan and ManBearPig is similar to the fight between Hulk and Abomination at the end of The Incredible Hulk.
Trivia: Outside the greenhouse where the abducted kids are being held are posters for the Weak Alibis, the Missing Notes and Rough Sects, which were bands that either appeared or were mentioned in the season 2 episode "Stuck on You." (00:37:40)