Actor Allusion: Of sorts. Professor Calculus' look is based on Professor Auguste Piccard, famous physicist and balloonist at the University of Brussels. When Bianca Castafiore is introduced to Calculus she mistakes him for a famous balloonist.
Ascended Fanon: The version of Tintin and Alph-Art by fan artist Yves Rodier almost became this, as Herge's former assistant Bob de Moor attempted to have it released as an official entry in the series. However, de Moor himself died before this could be done, and nothing came of it.
Author Existence Failure: Hergé died partway through his work on Tintin and Alph-Art; the unfinished draft has been published as part of the regular series of Tintin albums.
Author Phobia: Author Hergé was forced to listen to his aunt singing opera arias when he was a child. It led to a strong dislike of opera music, exemplified in the character Bianca Castafiore, whose singing usually scares away Tintin and Haddock or makes glass break.
Surprisingly averted with Tintin in Tibet, likely because it's politically neutral. Played straight in a number of markets when publishing Tintin in the Congo, however...
Red Sea Sharks is specifically banned from importation in Egypt, and only Egypt, for political correctness issues. Both its comic and animated versions, along with those of those for L'Or Noir and Tintin in Congo were skipped as well from the Arabic dubs, although they are still available in markets in their original versions.
There were a number of historical examples too. The Black Island and Tintin in America were banned in Nazi Germany due to the perception that they were sympathetic to Britain and America, respectively. Of course, the Nazi censors were not too thorough in analyzing which books to ban, as they did not ban King Ottokar's Sceptre, which involves the hero undermining a fascist coup.
Creator Breakdown: Hergé had one over Tintin in Tibet, though it ended up being one of his best stories anyway. See the Heartwarming page.
The earliest adventures, which appear out of place when one knows the entire series, were the product of Hergé just doing what he was told by his boss at Le Petit Vingtième, the Abbé Norbert Wallez, who was quite intent on using the comic strip as propaganda. After the first adventure, Hergé wanted to send Tintin to America immediately because he really wanted to write about Indians. Abbé Wallez however insisted he first write a story that would encourage readers to emigrate to the Belgian Congo. Wallez also liked to meddle in the private lives of his employees, setting up Hergé with his secretary and officiating at their wedding!
The Black Island was completely redrawn and In the Land of Black Gold redrawn and rewritten on the insistence of Tintin's British publishers Methuen.
In Brazilian Portuguese, the 90s Nelvana and 2011 film Tintins are Ma-Ti.
When the Belvision series got dubbed to English they got Paul Frees (Boris Badenov from Rocky and Bullwinkle) to voice Captain Haddock, Thomson, and Thompson
In the game based on the Spielberg/Jackson film, Tintin is Anders.
Postscript Season: Hergé apparently considered Tintin in Tibet to be the true finale of the series, with the following three books mostly being vehicles to experiment with his characters. Tintin and Alph-Art may have gotten things back on track somewhat, judging by the preliminary work Hergé did.
Reality Subtext: The political situations in various parts of the world often loom heavily over the fictional storylines. This is especially prevalent in the books written just prior to the Second World War and the Nazi occupation.
Tintin in the Land of the Soviets and Tintin in the Congo. Soviets was pretty much ripped completely from a book about Russia at the time. Hergé regretted a lot about Tintin in the Congo, such as the animal cruelty and the artstyle. He allegedly tried to get them removed from print, but at least got to assess some of his own personal issues with Congo.
One aspect of Shooting Star Herge was allegedly not very fond of was the portrayal of the antagonists as Jewish-Americans.
After Hergé announced at the end of Cigars of the Pharaoh that Tintin's next adventure was to be set in China, he was introduced to Zhang Chongren, a Chinese art student living in Belgium, who offered to consult on The Blue Lotus in order to avoid the stereotypes and caricatures typical of depictions of his homeland. Hergé accepted the offer, leading to a lifetime friendship. Zhang was even included in the story and known as Chang Chong-Chen. A humorous sequence has Tintin telling Chang about European stereotypes of China, which leads him to think that the Europeans are crazy.
Hergé was particularly meticulous in his research. He kept a huge collection of photographs, newspaper articles, and anything else possibly useful in future stories, and so many places and objects in the comic books are real places. For instance, the house of Prof. Calculus' Italian friend in The Calculus Affair is a real house that is still standing to this day. Furthermore, much of the scientific information in the books is accurate, or at least was accurate for the knowledge of the time, some apparent errors being a case of Science Marches On. In a odd case to Science Marching a 180 Degree Turn, one of Hergé's most well known "mistakes" was in depicting ice on the Moon (Explorers on the Moon), but since Indian astronomers have indeed found ice there, we probably owe him an apology.
The Other Darrin: In the BBC radio Productions, Haddock is voiced by Leo McKern (yes, THAT Leo McKern) in the first 6 episodes and by Lionel Jeffries for the remaining 6. Nestor changes to a new actor in the second half as well, and Castafiore changes actresses every time she appears.
Write Who You Know: For The Blue Lotus Hergé created a young Chinese boy Chang Chong-Chen (Zhang Zhongren in modern pinyin) inspired by his real-life friend Chang Chong-jen (Zhang Chongren) who he consulted on Chinese language and culture for the story. Chang also appears in Tintin in Tibet.
The reason why Hergé provides no explanation for Haddock's Deus ex Machina rescue of Tintin in Tintin Land Of Black Gold (when Haddock tries to explain how he got there, he's always cut short) is that it's actually a meta joke. The original version of Land of Black Gold was initially serialized in a newspaper in 1939 and 1940, but when Germany occupied Belgium in May 1940, that newspaper ceased publication, so "Land of Black Gold" was stopped mid-story. At this point Captain Haddock hadn't yet appeared in the series, so naturally he wasn't in the original Land of Black Gold either. Several other Tintin stories were published, first in another newspaper and then in the new magazine Tintin before Hergé decided to redraw Land of Black Gold in 1948. In the intervening stories Haddock had become the most significant character in the series besides Tintin himself. Thus it would've been odd if Haddock had been left out of the new version of Land of Black Gold, but on the other hand he didn't really belong to a story that had been scripted before he even existed. This is the reason why Haddock is virtually absent from the story until the very end, and why there's no explanation for his sudden appearance. The lack of explanation is Hergé's comment on Haddock "invading" a story he wasn't originally a part of. So there is a solution to the riddle on a meta level, but not in the actual text.
Because Tintin in the Congo is often not printed that much anymore due to racism, Al Capone mentions a diamond operation in the Congo that is never mentioned again and makes the viewer wonder if s/he missed an adventure. This may seem like a Noodle Incident to the uninitiated.
Short Run In Peru: The film debuted in Europe before opening in North America. Even then, it opened in Quebec one-and-a-half weeks before the rest of the continent due to the large Franco-Belgian comics market there. (And yes, if you were wondering, they got the original English version too, which allowed anyone from English Canada or the US willing to take the car trip to Montreal to catch the movie early.)