Author Phobia: When author Edgar P. Jacobs was two or three years old he fell down a seven meter deep old well. It took half an hour before he was able to be brought back up. This leads to a lot of stories where Blake & Mortimer are lost inside underground locations.
No Export for You: There were English translations of all published Jacobs stories, but for the longest time they were quite expensive. Cinebook has finally put out a complete set of Jacobs and post-Jacobs stories, although for some reason they published (and numbered) the Jacobs stories out of order.
The series continued after the original author's death.
Another example with the first part of The Curse of the Thirty Denarii due to the artist's death. The drawings have been finished by his widow.
Out of Order: The Cinebook translations interleaves the Jacobs stories with the later books, and does not respect the original order of the Jacobs books between themselves.
Saved from Development Hell: The second part of Professor Satō's Three Formulae was published in 1990, the first having come out in 1977. Part of the delay was because of Jacobs' death in 1987.
Sequel Gap: Not to Blake and Mortimer, but to Le Rayon U. A sequel was made by different writers titled: The Ardent Arrow. The first comic was made in 1967 and the second in 2023, leaving 56 years between those two.
According to The Other Wiki, there's been several attempts to adapt the series on the big screen, but none came to pass.
Ted Benoit (who drew The Francis Blake Affair and The Strange Encounter) pitched a story provisionally called Resurrection that revealed just how Olrik survived the nuclear annihilation of Basam Damdu's palace. It featured Olrik as the only survivor on an irradiated "ghost ship", the post-war ruins of London, and a climax involving US atomic bomb testing in the Pacific. The editors opted not to go ahead with it (and ultimately another story gave a different account of his survival), but Benoit did draw a cover as a commission for a fan.
Animated Series
Overtook the Manga: Only one of the continuation albums (The Francis Blake Affair) was adapted when the series was done adapting the Edgar Pierre Jacobs canon, due to the others not existing at the time it was made (the next one, The Voronov Plot, was published in 2000, over one year after the end of the animated series). As a result, the remaining episodes are original stories.
Artistic License – Paleontology: The Time Trap. The scene was an homage to one of Jacobs's favorite movies, a stop motion dinosaur flick of the beginning of the 20th century...
A memorable line by Mortimer in S.O.S. Meteors is "we don't even know how rain works!"
Uncredited Role: None of the English voice actors from the animated show were credited.
