There are numerous mismatches of footage in this film, cutting from cloudy location shoots in Scotland to sunny ones in North America.
When Case stops to change the car's tire, it's not the same vehicle as the Renault Megane Scénic he was supposedly driving.
The police uniform does not resemble any worn by Scottish police officers.
None of the characters pronounces "Loch" properly, which is supposed to have a guttural sound at the end of it, and is not meant to pronounced the same as "lock". While English and American people might do this, Highlanders would not.
No glass bottomed boats are used on Loch Ness, since the water is far too murky.
The nurses' uniforms resemble those of North American nurses, not of any worn by Scottish nurses at the time.
The water of Loch Ness is a deep brown, like a dark tea, from the tannins in the surrounding peat. It is not blue or green, or as easy to see through as it is frequently on this film.
When the police are gathered at the loch side, the vehicles they arrive in are 4-wheel drive vans made by what looks like the GMC company, with red flashing lights on the roof. The British police, when operating in rural areas, most often use Range Rovers or, more recently, the Land Rover Discovery which, while having 4-wheel drive, look nothing like the vans used in the film. Also, British police vehicles have blue flashing lights on the roof, not red.
Despite being set in and around Loch Ness, much of the film was obviously filmed in the United States.
HM Coastguard don't have any stations on inland lakes, nor do they have police-like powers. They're mainly a search and rescue operation and are never called upon to drop depth charges as part of their rescue operations.
Many of the "Scottish" characters have Irish accents.
The beer glasses in the bar are schooners of the North American type, not the usual pint glasses found in Scottish pubs.