Although Columbo has spoken Italian in several previous episodes, he claims to have never learned the language. As such, it's possible that Columbo makes up a new backstory depending on the suspect to whom he is speaking.
One of only a few episodes in which Columbo is physically attacked.
Columbo complains about the clams he ate the evening before and is offered 'vongele' by Fortelli. This is a reference to Rod Steiger's comments in W.C. Fields and Me (1976). He always blames 'bad clams' for leaving any production featuring Charles Chaplin.
This episode takes place in October 1994.
In the opening pawn shop scene, the pawn shop owner states emphatically that the gun he gives the murderer has never been fired. All firearms are test fired at the factory before they're shipped. This is especially true of Colt firearms, as they keep a record of the test firing at the factory. However, this is only like a car salesman telling a customer that a new vehicle has "never been driven" even though it must have at least been driven off the assembly line, and on and off at least one car transporter.