When Columbo goes to the private detective, hired by Hugh Creighton (Dabney Coleman) to check on his mistress, the series pays homage to classic film noir "private eyes". The name of the private eye is Sam Marlowe. This is a combination of the names Sam Spade and Philip Marlowe. Sam Spade was the fictional private detective of Dashiell Hammett's 1930 novel, The Maltese Falcon. Phillip Marlowe was the fictional character created by Raymond Chandler in his 1939 novel "The Big Sleep". Additionally, there is a statuette of a black bird on the windowsill in Sam Marlowe's office that looks like the famous bird from The Maltese Falcon (1941).
When Columbo & the ticket lab tech are getting ready to conduct their experiment Columbo states that in all the time he has owned his Peugeot 403 he has never had the top down. Columbo must have forgotten that when he was at the burger stand with Peter Hamilton (Leslie Nielsen) in Season 1, episode 2 "Lady in Waiting" the top on the car was in fact down. Columbo must have also forgotten that in the Season 5 finale, Last Salute to the Commodore, he has Sergeant Kramer (Bruce Kirby) put the top down for their ride to the harbor with Sergeant "Mac" Albinsky & Charles Clay (Robert Vaughn).
During the scene when Columbo is looking at photos on the wall of people that were caught by the speeding camera, the bottom right picture is actually Peter Falk in disguise.
This is the second Columbo episode in which Dabney Coleman appeared. He played Detective Murray in Double Shock (1973).