At the luau, Slater mentions that Cynthia, the girl he "saved" earlier, would be going to Bayside during the senior year. But nothing is mentioned of her during season 4.
Jessie: You need a friend?
Zack: Wouldn't hurt.
Slater: How about five friends?
Slater: Hey, there was no fight! Where is that kid?
Kelly: Hey, that was no kid, that was the next Zack Morris!
This is the sixth episode where the entire cast excluding Dennis Haskins were not in school, the Max, or any places as they were in the school episodes, and it's the last episode in the Malibu Sand Beach Club.