The title comes from the play/movie "Deathtrap (1982)" by Ira Levin that involves many plot twists. It holds the record as the longest-running comedy-thriller on Broadway.
When Frasier (Kelsey Grammer) points to the skull to show it has been fractured, he refers to the portion as the temporal bone. However, he's actually pointing to the frontal bone.
The Crane's former house number is 5958.
Frasier ironically gives himself his own clue to the real origins of the skull when he quotes to Niles, "Murder most foul.", which comes from Hamlet.