Deliberate "mistake": Loch Ness is portrayed as a clear lake, as shown in the underwater scene. In real life, Loch Ness is so murky there is only six feet of visibility. Obviously deliberately done for the sake of the storyline.
The Water Horse: Legend of the Deep (2007) - 2 mistakes
Factual error: The taking of the famous "Surgeon's Photo" of the Loch Ness Monster from real life is worked into the fictional story of the film, which takes place during World War 2. The Surgeon's Photo was actually taken in 1934.
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