When Detective Velez leaves hospital after being grazed by a bullet, the wound is closed with butterfly dressings. Their use would not become widespread for another 20 or 30 years.
A cinema marquee is showing Touch of Evil (1958). The film is set in 1957 Havana, but Orson Welles' film was not released until April 1958. That film also features an honest cop trying to overcome a corrupt justice system.