The first episode of Good Morning, Miss Bliss has a character ask if she's speaking with Miss Bliss, or her evil twin. This is a reference to Hayley Mills' appearance in The Parent Trap.
Dawson Casting: Averted. The actors playing the main characters match their ages, though Screech may have skipped a grade or two somewhere. It's most noticeable in the Miss Bliss episodes when he's a full head shorter than everyone else in the grade.
Elizabeth Berkley ("Jessie") was somewhat of a borderline case, as she was 17 when her character was introduced, pushing her to around 20-21 by the time the series wrapped (playing a high school senior).
This was also averted in the spin-off. All the teen characters were played by actual teens although a couple did push into the twenties towards the end and only Lindsey McKeon graduated the same year as her character.
Edited for Syndication: Good Morning, Miss Bliss has only ever aired in syndication as Saved by the Bell: The Junior High Years. The changes include replacing the original opening and closing credits with those from Saved by the Bell (only subbing in the different actors for the opening), adding in a cold open to each episode with Zack Morris as narrator (to bridge the two effectively separate continuities) and switching out the incidental music with the more familiar synth stings (which jar rather strongly with the more laid-back and subdued atmosphere).
Fake Mixed Race: Zack's out of nowhere Indian heritage is the focal point of one episode. Afterwards, it never brought up again. Ironically, Mark-Paul Gosselaar is mixed race, just not part-Native American (he is part-Indonesian on his mother's side).
Donna Martin transferred over from West Beverly for a few episodes.
Carrie Heffernan was Zach's boss/love interest when he was working at the beach during the summer.
Screech's cousin? Then-Indianapolis Colts quarterback (and current coach of the San Francisco 49ers), Jim Harbaugh.
Hardcore NFL fans will recognize Bob Golic (who played Mike) as a defensive lineman for the Cleveland Browns during the 1980s (or for being the older brother of fellow defensive lineman and Mike and Mike in the Morning co-host Mike Golic).
Not to mention who knew that Sonya Blade went to Bayside?
I Am Not Spock: All of the actors have gone through this at some point. Dustin Diamond, Lark Voorhies, and Dennis Haskins in particular never escaped their most famous role. Of the three, the former is the only one who hasn't embraced this. Showgirls tainted Elizabeth Berkley's career and has been Spocked as Nomi Malone instead. Mark-Paul Gosselaar, Mario Lopez, and Tiffani Thiessen, on the other hands, found success after the show ended.
Playing Against Type: Most people that know Mr. Belding is a very strict but a kindhearted person. However, in one particular episode, "The Yearbook", he was more than willing to restrain Zack while Slater was gonna punch him. Zack got out of it with his classic Time Out power, and boy did Belding learn the hard way that he can't be sadistic without consequences.
What Could Have Been: Susan was a very fun character, but alas, she joined the recurring cast of The College Years very late into its run, as the show was nearing cancellation. If the show had lasted more than one season, she would have surely continued to play a larger role.