* {{Anvilicious}}: Particularly in the later seasons, nearly every episode took on a "cause" of some sort. Whether ghost surgery, advertising alcohol on TV, DrugsAreBad, or fraternity hazing, there was always some cause-of-the-week that the show tried to hammer home its message about as unsubtly as possible.
** It didn't help that Quincy (and in one episode ''Asten'') was not above delivering speeches about the subject.
* CounterpartComparison / SuspiciouslySimilarSubstitute: An odd example with two characters that had one episode each- actor Gerald S. O'Loughlin played the role of Jake Cutter in season 7's "Smoke Screen", a city insurance and arson investigator brought in on the episode's arson case. In season 8's "A Loss for Words", O'Loughlin returns as Arnold Chatham, an arson investigator that has worked for the coroner's office for 20 years, who has hidden his illiteracy. Same actor, same role, different names, different specific departments.
* HarsherInHindsight: In "Let Me Light The Way", Quincy attempts to persuade the law-enforcement bureaucracy to support the nationwide use of rape kits to collect evidence of sexual assaults. The penny-pinching reluctance of an FBI official to fund Quincy's plans seems a lot harsher when one considers that, forty years later, thousands of the rape kits which RealLife [=ME=]s and activists like Quincy worked so hard to make available have been left sitting in the evidence room, collected but never analyzed, because it would cost money to ''test'' them.
** Many of the issues that Quincy fought for in the 70s to 80s STILL persist in RealLife as of 2015. Drug companies shelving vital medications because there isn't enough profit? Plastic surgeons being allowed to practice with only superficial medical credentials and no real certifications to their skills? Companies cutting corners on safety to save a few bucks? Just to name a few...
** The mind control and interrogation techniques seen in "Sweet Land of Liberty" were very real- the episode was based on the government's MK Ultra experiments.
* NeverLiveItDown: "Next Stop, Nowhere," an alarmist polemic about the evils of punk rock which has naturally become a camp classic among punk fans in the same vein as ''Film/ReeferMadness''. It's dominated the show's reputation ever since.
* SeasonalRot: Quite a few people find the later seasons less enjoyable because of their tendency towards [[{{Anvilicious}} preachiness]].
* SomeAnvilsNeedToBeDropped: For all the complaining about the series being preachy, this is exactly why such a change happened. Many of these social issues needed to be addressed.
* SpecialEffectFailure: The apartment fire effect in season 7's "Smoke Screen" is a terribly done overlay that doesn't look close to real.
** For the most part, the makeup job used in "The Depth of Beauty" is incredibly well done. But they only applied it during the interview scene where the woman unmasks, meaning closeups of her eyes in other scenes lack the heavy scarring.
* TechnologyMarchesOn: A teenager in the HollywoodTourettes episode was a movie buff who couldn't enjoy movies for fear of making outbursts in a public theater. A few years later watching movies at home using a VCR would become commonplace.
** Asten forces Quincy(and much of the staff) to carry beeping pagers at one point. Pagers are, of course, obsolete now, and Quincy would be carrying a cell phone these days.
* TheyWastedAPerfectlyGoodCharacter: Dr. Hiro from "Has Anyone Seen Quincy?" is the chief corner of Los Angeles, but only had one episode and is forgotten about afterwards.
* TheyWastedAPerfectlyGoodPlot: "What Happened To Morris Perlmutter?", in which a gripping murder mystery is inexplicably sidelined in favour of a PSA about the title character's hearing for almost the entire episode. (Why yes, this ''is'' [[SeasonalRot from the final season]], how'd you guess?)
** That is to say, the murder that opens the episode is quickly shoved to the sidelines. A blood test against a possible suspect turns out negative, until it's revealed the suspect is anemic and requires frequent blood transfusions, which caused the negative result... then nothing. That little discovery ends the murder story and it's not touched upon again.