Lisa, Zack & Screech all talk to JB as if they have known her since she was little. However, they have only known Slater for approximately four years, so them knowing her from a little girl, as implied, wouldn't be possible.
During the final 2 seasons of Saved by the Bell, most notably the season with Tori and the one following it, look for actor Casper Van Dien in the background of some episodes. He appeared in many scenes throughout the final 2 seasons as a random background extra, most notably in the locker hallway scenes. This was before he made it big in Hollywood.