Revealing mistake: The raid took place at Xmas in 1951. In homage to this fact, the characters wear big coats and one of them even rubs his hands together and goes "Brrr." Yet the movie was filmed in the height of summer. Trees in the background of scenes in London are full of leaves, we never see any mist in exhaled breath and the lighting levels and shadows indicate a high, bright sun.
Factual error: The Volkswagen Campervan that is used at the beginning of the film has a Zürich number plate, yet the cantonal coat of arms to the right of the number plate is that of the canton of Ticino (red and blue stripe). This is incorrect: The coat of arms should have been a white-blue stripe, which is the coat of arms of Zürich Canton and would correspond correctly to the number plate.
Continuity mistake: At breakfast, the morning after Maria has just arrived at her Uncle's house, the uncle calls Maria's father a coward. He has a glass of brown drink in his hand. He's just taken a drink and the glass is 3/4 full. Maria angrily refutes that her father was a hero and the glass, still in his hand, is now full to the brim. (00:19:20)
Continuity mistake: When the brothers are standing on the rocks on the beach, the clouds change back and forth behind Stephan.
Continuity mistake: During this scene, the female lead, Freya, is being attacked by the Moorwen youngster in order to eat her. When above her, the Moorwen's saliva is dripping onto her face, cut away to the monster, as it hears the main characters coming to her rescue. Cut back to Freya and there is none of the saliva on her face, another cut back to the creature and a final cut back to Freya, her face is now covered in saliva again. (01:27:30)
Factual error: Ben stops at a rest area near Hope, BC. He is headed for Vancouver and Vancouver Island. Leaving the rest area, he turns right, as he should, to head for Vancouver. The highway sign points left for Hope, BC, and right for Vancouver. I've been at this rest area, and the direction he turns toward Vancouver is correct. However, the next shot shows him going through Hell's Gate tunnel, which is north of Hope. He would have had to turn left, go through Hope, and 40 or so miles north to go through the Hell's Gate tunnel. The next scene shows him on the ferry to Vancouver Island, which was in the direction he was headed when he turned right from the rest area. There would be no reason for him to turn around and go through the tunnel, as he was already heading in the right direction.
Factual error: One of the women in the group picks up a piece of calcite (Iceland Spar variety). It is obviously calcite because of the very obvious rhombohedral cleavage and other visual indicators. The sample is later identified as ringwoodite. Ringwoodite is cubic with no reported cleavage. Even if it did exhibit cleavage, it would not be rhombodedral.
Continuity mistake: When Despereaux fights the cat in the rat arena, he hides behind a blue ball of yarn. When the cat hits the yarn, causing Despereaux and the yarn to fly in the air, in the next shot, the ball of yarn vanishes and never reappears again.
Character mistake: Throughout the movie, all of the drill sergeants and First Sergeant Morley are wearing their drill sergeant badges too low. The badge is supposed to be centered on the right jacket pocket.
Character mistake: The professor identifies the "sea monsters" as plesiosaurs from the Pleistocene. Plesiosaurs became extinct at the end of the age of dinosaurs, nearly 60 million years before the Pleistocene. Of course, the Loch Ness Monster might be an exception.