Columbo's wardrobe consisted of Peter Falk's own clothes, including the high-topped shoes and shabby suit. Falk bought the famous raincoat, which first appeared in "Prescription: Murder (1968)," for $15 in 1967, when he got caught in a New York City rainstorm. A life-long cigarette smoker, Falk added the cigar as a personal touch.
The original plan was for a new episode to air every week, which would have meant shooting an episode every five days. As a motion picture star, Peter Falk refused to commit to such a busy schedule. The network arranged for the Columbo segments to air once a month on Wednesday nights.
Peter Falk frequently added in unscripted improvisations such as asking for a pencil, searching for something in his pockets, asking a character to repeat something, rambling about irrelevant trivialities, or adding in a line about Mrs. Columbo. Falk did this to frustrate and annoy his fellow actor (usually the suspect) and generate a genuine "get to the point" moment.
When this show was renewed for a second season, NBC brass wanted Columbo to have a sidekick. Richard Levinson and William Link conferred with Steven Bochco, who was writing the script for the season opener, and together they hatched the idea of giving Lieutenant Columbo a dog as a partner. Peter Falk felt his character had enough gimmicks, between the raincoat, cigar, and Peugeot. When he met the lethargic, drooling basset hound that had been plucked from a pound, Falk knew it was perfect for Columbo's dog.
The original character concept for Columbo was a smooth-talking, stylish, cultured personality. Bing Crosby was the first choice, but he declined. When Peter Falk auditioned, he brought an entirely different dimension to the role with his aimless chattering, scattered mannerisms, and disheveled appearance. The producers weren't certain if audiences would accept a police detective looking like a bum, but the show's premiere was an instant hit.