Two mistakes I know of for now: the Promo on stand 101 (page 238) is a fake: the text is for another comic series (De Katamarom) from Dupuis, the editor of the Smurfs. I have seen the same stand with the correct figiure (a catlike space monkey thing), and it exists in French (Le Scrameustache) as well.
The Promo torch bearers are placed in the wrong order: Picture 201 is Text 202, picture 202 is text 203, and picture 203 is text 201. For this reason is the Belgian Olympic torch bearer sometimes ridiculously expensive, while it isn't rare at all.
Oh, and a third one: beneath 51903 (Xmas Papa), they have forgotten the years it was produced
All very understandable in such a catalogue, nothing serious, but it may be interesting to know!