[9] In August 2024, author Frank Tallis said that while the latest episodes covered the last published book in the series, "when you exhaust the books, if you've let the idea develop and gain its own momentum, in a way it doesn't need the novels or the author anymore… but doesn't in any way stop me from writing proposals or plot ideas!

"[13] In interviews with Austrian outlets as the fourth season was broadcast in Austria in December 2024, the producers left open whether that was the definitive end of the series or whether there could be a continuation in the future.

[17] Locations included the Vienna State Opera house and Volkstheater as well as Landstrasse, Hauptstrasse, Herz Jesu church, Votivkirche, St Charles Borromeo Church, Griechengasse, Molker Steig, Schreyvogelgasse, Dreimaderlhaus, Schonlaterngasse, Alte Schmiede, the Vienna University Archive, the Billrothhaus (Vienna 9), the Natural History Museum, Palais Pallavicini, the Burggarten park, the Stadpark, the Arsenal, Otto Wagner Hospital, Villa Mauthner von Markhof, Kirche am Steinhof, the Riesenrad (big wheel), Stephansdom, Sankt-Ulrichs-Platz, Palais Pallavicini, National Library, Zentralfriedhof, Friedhof der Namenlosen, Museum of Military History, Cafe Morgenstern, Café Sperl and Café Bräunerhof and features the Beethovenfries.

[18][19] Series 2 was also filmed in Vienna and Lower Austria, featuring such locations as Hotel Imperial, the Stadtpark, Kursalon Hübner, Schönbrunn Palace, the Museum of Military History, Traungasse, Lagergasse, Buchfeldgasse, Florianigasse, Schulhof, Kirche am Hof, Franziskanerkirche, Michaelerkirche, Palais Collalto, Kartäuse Mauerbach (monastery) and the Franzensburg in Lower Austria.

[18] Filming of Series 3 was split between Budapest (including the Párisi Udvar Hotel and the Vígszínház Theatre, Bedo House, Postal Museum, the National Museum of Hungary and the Hazai Bank) and Vienna (including the Loos House, Belvedere, Dr Ignaz Seipel Platz, Jesuitengasse, Michaelerplatz and the Hofburg).

'[27] The Guardian's Emine Saner, giving three out of five stars to the first episode, remarked that the series was similar to Thompson's prior work on Sherlock, particularly in its leads' dynamic and the presentation.