Jacques Perrin says in his commentary that his team tried to include emperor penguins (Aptenodytes forsteri) in the film, but weather conditions interfered, so they had to be satisfied with king penguins (Aptenodytes patagonicus) instead. Some years later, the makers of March of the Penguins (2005) succeeded in making an emperor penguin movie.
The trivia item below may give away important plot points.
The scene where the goose gets stuck in industrial sludge was deliberately staged by the producers and the bird thus was immediately freed after shooting. Also, while the wounded Tern beset by crabs was not a staged scene, the bird was rescued by the crew at the last moment after shooting the action. When the crabs are seemingly devouring the injured bird, it is actually a dead fish that has washed up on the beach.