The dog who played the title role of "The Dog of Flanders" (named Patrasche in the movie - the same name Peter Paul Reubens named his dog) is the same dog who played the title role in "Old Yeller".
There are several Lassie connections in this film. The dog trainer on this movie is Frank Weatherwax, the brother of Lassie's trainer, Rudd Weatherwax. Donald Crisp,who plays David Ladd's grandfather here, played the father in "Lassie Come Home" (1942)and had roles in three "Lassie" movies. Crisp was also James Brown, the kirk yard keeper, in Disney's Greyfriars Bobby: The True Story of a Dog (1961).
At conclusion of film (no end credits): "A Dog of Flanders was filmed entirely on location in Holland and Belgium. We wish to thank all the people of those two countries whose kindness and cooperation made this possible. We further wish to express our sincere gratitude to Father Weleerwaarde Heer Vanheirkom for permitting us to film the interior of the Cathedral of Our Lady, Antwerp."