The boy talking on the phone at The Max is D. Danny Warhol (credited as Dan Charles Zukoski), the actor best remembered as the pizza guy from Home Alone (1990).
This is the first appearance of Zack's mother.
Mark-Paul Gosselaar was 17, Dustin Diamond was 14 and Mario Lopez had just turned 18 when this episode aired.
Zack's Mom Returns later in the season In the "Home For Christmas" two-parter.