Despite the name this episode takes place nowhere near Loch Ness (an episode of the later series "The Scooby-Doo Show" does though).
We meet one of Shaggy's family members. Family members of Shaggy/Scooby, Daphne and Velma will appear throughout the series and its incarnations. Fred's never appear until "A Pup Named Scooby Doo" in the 1980's
When Scooby arrives with thier midnight snack, Shaggy is standing in the open doorway of his bedroom. The next shot is of a ghost coming up the stairs. When we cut back to Scooby and Shaggy, they appear to be standing in front of the same door, which is now closed, and Daphne and Velma pop their heads out a moment later.
As they're leaving the picnic area, Granny and the dog from The Harlem Globetrotters TV series are visible in the back of the Globetrotters bus. A few minutes later, the seats they were occupying are empty and they do not appear anywhere else in the episode. While Daphne is visible in the bus in this shot, Freddy is not although he's seated next to her a few moments later.
Right before they find the secret passage in the bookcase, Shaggy, Scooby, Meadowlark and Curly enter the room behind a large spiderweb. There's a huge jump as they move from the left to the center of the screen, as if there are several frames of film missing.
While everyone is discussing going to investigate the sea serpent, all of the Globetrotters are lined up together. Suddenly Meadowlark is standing across from the rest of them.
Scatman Crothers is credited as Benjamin Crothers.