When Virgil remarks that vampires can't cross running water and that Moska must have been destroyed, Max says "Hello, Virgil! News flash! The garlic didn't work, neither did the mirror." Virgil wasn't there when they didn't work however, and wouldn't have known that. It's kind of odd also that Virgil seemed to think nothing of Moska sprouting insect wings and spitting acid--not abilities documented in legends of classic vampires.
Max: Like Norman would say, "It's party time!"
Max: You'll have to excuse me, teach. I got a message from an amoeba.
Mrs. Fudder: A message from an amoeba? (She views her amoeba, who give a message that says, "Have a nice day.")
Virgil's means of summoning: In science class, when Max is looking through a microscope, he receives a message within an amoeba in a slide of pond scum. The message was "Max take the portal at the park, Virgil!"
Educational Epilogue: The common house fly
This episode was probably inspired by the Fly playset from the Doom Zones line of the Mighty Max toys.
Virgil also sends Mrs. Fudder a microscopic message. The message was "have a nice day."