The only episode of the series not to feature the Mystery Machine (aside from in the credits).
The character Tomina Kasanski's code name is "Ice Princess." She also has short blond hair and wears aviator sunglasses. She's a nod to LT Tom "Iceman" Kazansky, famously portrayed by Val Kilmer in Top Gun. The beginning of the next episode even has Shaggy and Scooby quoting (most of) the "I feel the need - the need for speed!" quote made famous by that film.
While on the plane ride, Mrs. Dinkley is telling Velma how she met Enrique. Mrs. Dinkley says "The summer flings, they don't mean a thing. But oh, oh, oh those summer nights." This is a line from one of the songs in "Grease".