Continuity mistake: Columbo stops Mr. Finch on the road after following him from Biltmore hotel; as Columbo is speaking with him, the cigar in Columbo's hand is always in Finch's shot, even after we see Columbo place his hand on the roof. Plus after we see him put his hand down, the cigar ash keeps going from 1" to nothing. (01:44:20)
Continuity mistake: At the end, when Columbo is demonstrating on the mannequin, his cigar changes position between shots.