* BaseBreakingCharacter:
** Marc Hoffmann is divisive; he does have his fans, but some part of the fandom of the series says that he was a bad commisar and a bad thing to the series because his romance with Nikki sort of overshadowed Rex and he did not take the missions with the seriousness he should have.
** Marco Terzani has his fans as well, but many see him as [[ReplacementScrappy an unworthy subsitute]] for the more beloved Davide Rivera. It doesn't help that it is thought that the part of the series in which he is the commissar was the worse.
* FirstInstallmentWins: It is agreed upon that the seasons with Richard Moser were the best. The other seasons are more controversial. The Italian seasons are seen as inferior even among people who liked them because the series began losing its comedic tone and Rex was getting gradually reduced to a device to arrest the MonsterOfTheWeek.
* GermansLoveDavidHasselhoff:
** The series is very popular in Austr'''al'''ia, even being the subject of a recurring parody ("Inspektor Herring") on a local sketch comedy show.
** It's also quite popular in Russia - it gets regular reruns up to this day and inspired a semi-ForeignRemake called ''Mukhtar Comes Back'' - the dog's nickname was borrowed from an older Soviet movie, but the series overall are reminiscent of Rex. In the same country, this happened to Davide seasons; while Davide is well beloved by the fans, his seasons had bad ratings in Italy but were more popular in Russia.
** Popularity of series in Poland led to making its own version as well, ''Komisarz Alex'' ("Inspector Alex") and it gained a popularity among the viewers.
** The sheer amount of German Shepherds being named "Rex" in Vietnam speaks for the spread of the show.
** It was also well-known in the Czech Republic, with the Prima network airing this show by the time it aired and re-ran frequently.
** It's also popular in both Portugal and Canada with both getting their own versions, ''Inspector Max'' and ''Series/HudsonAndRex'' respectively.
* HarsherInHindsight: The 2004 episode "Finally The Monster is Dead" revolves around the murder of a respected businessman who is discovered to have been sexually abusing his daughter for years. This show was made and set in Austria at the time. [[http://en.wikipedia.org/wiki/Fritzl_case Do the math.]]
* HoYay: Alex Brandtner and Christian Böck. They start calling each other by their first names while Höllerer still referred to him as "the new guy" or just "Brandtner". And then, in an early episode, Alex tenderly wiped blood from Christian's face. Not to mention that they always stand very close to each other.
* PeripheryDemographic: Rex's cute personality made this show loved by children, although the series often has very serious cases, involving even rape.
* QuestionableCasting:
** Kaspar Capparoni's tough demeanor was considered unfit to the role of a policeman.
** Francesco Arca looks too pretty to look like a serious policemen.
* RetroactiveRecognition:
** Creator/ChristophWaltz appeared in the season 3 episode "Der Puppenmörder", playing the BigBad, years before his breakout role in ''Film/IngloriousBasterds''.
** Sidekick Stockinger is played by Karl Markovics, years before his most well-known internationally role as Sally Sorowitsch in ''Film/TheCounterfeiters''.
** Musical theatre fans can spot Uwe Kröger as Paul Koblenz, before he becomes a household name with ''Theatre/{{Elisabeth}}'' as Death. [[note]]Which gets HilariousInHindsight, as the man gets only about a minute of screen time before getting shot dead, and reappearing later as a face-down corpse.[[/note]] [[https://www.youtube.com/watch?v=ExE03Tc2yN0 Watch it here.]]
* RomanticPlotTumor: Marc and Niki's romance had some backlash because it sort of overshadowed Rex. When the romance was introduced, there was fear that the series would become too HotterAndSexier for its own good.
* TearJerker:
** [[spoiler: Moser's death]], ''in spades''. The fact it comes ''[[YankTheDogsChain right after]]'' the guy has settled with a girlfriend he's happy with is bad enough already ([[Creator/JossWhedon "happy people make for boring television"]] indeed), but the "PleaseWakeUp" scene at the end manages to make it even worse. [[spoiler: Rex does the final "Please, Wake Up" with a squeaking animal's toy it is holding in its mouth, before it gives up and sadly leans its face on Moser's dead body]]. And then the screen fades to white.
** The ending of the 11[[superscript:th]] season, in the chapter "Lontano da qui" (Far from Here). [[spoiler:Barbara]] tries to shoot Fabbri, but [[spoiler:Rex jumps over him so he does not get shot]]. Fabbri is saved, but [[spoiler:Rex lies severely wounded because he received the bullet]] (he gets better). The credits have the sad instrumental song instead of "My Name is Rex" and keep the scene.
** "Un Uomo Solo" has a sad but beautiful ending scene. Gori reads a letter of the recently late Donatella, in which [[spoiler:her love to him is shown]].
** Then [[spoiler:Lorenzo Fabbri's death]]. He gets trapped in a car [[spoiler:and fails to deactivate a bomb which was put there by Donato Tramontana]]. Rex returns to see all that, [[spoiler:to see Fabbri's failure and a short farewell gesture before dying in the explosion]]. It ends with Rex crying and a sad music.
* TheyChangedItNowItSucks: The more serious approach the Italian seasons gradually added was not well received by the fandom. Another disliked change was that Rex was slowly becoming more passive than he was in the Austrian series and became just a device to arrest the criminal.