Just one more thing.

Spanning 4 decades, everyone's favorite dishevelled detective is instantly recognisable the world over. So how come now there's no trace of what his first name was? Many people know it is Frank, but there's no episode to be found today where it's ever mentioned. Columbo is reported to have only answered "Lieutenant" as his first name when he was asked what it was.

Some fan sites point to clues - a badge briefly shown on screen with his name on it, a parking permit you need to freeze-frame to read etc. That's not the way many remember it though, and are sure he was called by his first name in several episodes.

What is certain is that his wife never appeared on screen, although she was mentioned in practically every episode. Did she call him "Lieutenant" at home, too?

Lieutenant

He was first portrayed by Bert Freed in 1960, then Thomas Mitchell in 1962, but best known by Peter Falk from 1968 to 2003.His fist name was never mentioned in the credit; they only said "Peter Falk as Columbo". 

There is an interesting twist regarding the disclosure of Columbo's first name, but it doesn't really help clear up the Mandela Effect. In order to thwart counterfeiters, sometimes false details are placed in whatever is being protected. This was a favourite trick of the map makers of old, the idea being the counterfeiters would also copy the false item so make it obvious what they have done. It's even suspected to be an explanation for a different Mandela Effect, the Bermeja Island one. This happened to Columbo's first name, because Fred L. Worth wrote a book called The Trivia Encyclopedia where he said Colombo's first name was Philip - something he invented as a copyright trap. It worked, because later this fact appeared in the board game Trivial Pursuit, and formed the basis of legal action against the makers of the game.