The night before the departure of the Three Investigators Jupiter checks the paintings again and leaves the room. There he meets another guest of the hotel, who is Oliver Rohrbeck, the German voice of the audio books of the Three Investagators.
At the Beginning of the movie, when the three boys arrive at the junkyard, there's a customer who's interested in the parrot and peeks at the boys is Andreas Fröhlich, the German voice of Bob Andrews in the German audio books.