Visible crew/equipment: As Joe approaches the third car with the bad guy in it, there is an unknown man, possibly a crew member, reflected in the back window where there wasn't a man before.
More mistakes in Dragnet 1967
Trivia: In this episode, the murder victim's name is given as Reiko Hashimoto, and at one point, Gannon shows Friday a couple of photographs of her. Reiko Hashimoto was the maiden name of Reiko Douglas, the wife of comedy writer, author, and perennial talk show guest Jack Douglas, and the photographs used are of her.