The "Klopstokian" accent sounds very Swedish.
Final appearance of Velma Dinkley as an adult until Scooby-Doo on Zombie Island (1998). In the intervening years, A Pup Named Scooby-Doo (1988) depicted her, Fred, Daphne, and Shaggy as preteens.
The President broadly resembles the then-incumbent [link-nm0001654], but is younger, sharper, and more active.