Revealing mistake: During the opening credits, as a crab descends past the periscope, the string attached to the crab is visible.
Revealing mistake: When Spats Columbo's gangsters are being searched for weapons at the Florida Hotel, the man doing the pat search can be seen placing the gun behind the gangster's leg, just before it supposedly drops out of his trouser leg.
Revealing mistake: Rock Hudson angrily picks up Doris Day from her bed, blanket and all, and carries her through town to his apartment. When he is walking down the sidewalk, the blanket slips and the supporting wooden board underneath Doris Day is visible. This made carrying her easier.
Revealing mistake: When Wilby is in the car being chased by the police officers while he is a dog, in some scenes the dog is a real dog and in other scenes it is just a person in a dog costume.