The episode's title references the mystery board game "Clue" in which players must determine who had killed Dr. Black, in what room and with what weapon. Clue is the game that Sam brings to Olivia's apartment to play with her in the middle of the night. This reference was also foreshadowed during the previous episode: when two of of the observers go to see the movie Back to the Future (1985), there is also a poster for the movie Clue (1985) hanging at the theater.
When Diane Kruger's character tries to remember someone's name on the telephone, she asks "Gorlami?". The character Aldo Raine uses this name as an alias in Inglourious Basterds (2009), also starring Kruger.
Walter shines an ultraviolet light on the cancer riddled arm and says the older tumors will refract a different color; indeed the tumorous handprint glows red. Refraction is the bending of light; the hot air above a black surface in summer bends light and gives us wriggly, heat roil images. When something absorbs UV light and subsequently glows a different color than UV it is called fluorescence.
The trivia item below may give away important plot points.
The first shot of Mrs. Lane shows her doing a jigsaw of two fingers almost touching. That is from the central (Creation of Adam) panel from the Michelangelo painting on the ceiling of the Sistine Chapel. The image represents God giving the spark of life to Adam. In this episode the bad guy steals the spark of life, or at least health, from his victims.