Mob muscle Freddie gives Columbo a business card with "Copo Tutti De Copo" on it. It's hard to tell whether this is humor or error. The card text makes no sense in Italian; however, it is similar to "capo di tutti capi", the Mafia Godfather's title "boss of all bosses".
Columbo hasn't been promoted by the Los Angeles Police Department in several decades. He has been a lieutenant for at least 35 years.
Peter Falk wanted to play Columbo for one last time after this mystery. In 2007, he had chosen a script called "Hear No Evil", which was to be renamed "Columbo's Last Case". Unfortunately, it didn't get the 'green light' by a network, and Falk got diagnosed with dementia soon after.
One actor in this show almost matches Peter Falk for longevity in the series: John Finnegan (who plays Sean Jarvis) had a 31-year run in the series starting in 1972. He appeared with Falk in 13 episodes and was also a regular guest actor in many popular cop shows of the '70s. He died one year after Falk.