The Left Hand of the Magician - S1-E5
Continuity mistake: When Luca is looking at Fujiko in the tiger cage for his quasi-stepbrother's act, he is gripping the chain-link fence. The fence is drawn in a strange way, seemingly missing several sections, but besides this animation oddity, it is clear that his right hand is in one shot next to large vertical metal bar (partially covered by it even) but in a different position in the side view that follows. (00:12:55)
The Left Hand of the Magician - S1-E5
Plot hole: Luca draws the sketches of a magic trick, but they contain a fatal flaw that would kill whoever is doing it. He is hospitalized so he takes no part in the setup, so there is basically no chance that the flaw would go undetected. Other people are building the stage and device and they'd do at least a couple of tests before debuting a death defying stunt with live arrows and fire during the show.
The Left Hand of the Magician - S1-E5
Plot hole: Luca is the one who set a deadly trap, but somehow doing that he realises that it was his rival that killed his dad, and accuses him of trying to hurt Fujiko...which he did himself! In fact, this begs the question; if the ringmaster wanted to be the one and only to have access to his father's tricks, why was Fujiko the one doing the magical act? It would have brought fame to her and kept him in the shadows. If he knew that the act was flawed (and it was not, since it works), another death on stage would have tanked the show forever, so obviously it was not what he was after either.
The Left Hand of the Magician - S1-E5
Factual error: Interviewing the circus crowd, Lupin talks with a guy that is counting a bunch of 5 euro banknotes. The notes lack serial numbers, but even if we consider okay the lack of detail in such a tight close-up where they bothered to reproduce with pretty good precision the rest of the filigree, they surely are shaped wrong, being at least a 30% wider than an actual 5 € note. (00:06:40)
The Left Hand of the Magician - S1-E5
Continuity mistake: In the buff acrobat's flashback/narration of Fujiko's seductive ways, she is pulling Luca in with the towel, but Luka is facing away from her in the first shot and towards her in the second. (00:05:40)
The Left Hand of the Magician - S1-E5
Factual error: The contract signed towards the end is written with the wrong characters - it is missing accents on vowels that require it in Italian "è stabilito", "così." (00:19:15)
The Left Hand of the Magician - S1-E5
Continuity mistake: Fujiko opens the suitcase on her motorbike with the left arm, right arm, left arm, depending on the camera angle. (00:19:45)