*This post is incredibly long

Now for decades people have always have always talked about the continuity issues with Saved by the Bell such as the transition of Good Morning Ms. Bliss to SBTB finding it weird that three students and their principal just moved to California and claimed to live to there all their lives and have friends (Jessie and Kelly) who they've supposedly known for years despite not being GMMB and never being mentioned at all. Now obviously in the real world SBTB was a hard reboot of Good Morning Ms. Bliss (although not having the smoothest transition). But I also have a theory that some episodes including the GMMB years are us seeing alternate universes of the Saved by the Bell as it could explain the major continuity issues the show has had that could be explained in our world but in their reality makes no sense. I will list the major universes that could explain some big continuity issues

Note: There are infinite amounts of realities according to alternate universe theories; so for me any contuinity error I see in a show whether small or major I deem it as alternate universe were seeing. Since there are infinite amounts of realities not every universe is drastically different, some universes are identical with a slight differences (i.e like a person not existing or an event not happening or happening differently) and some unverses have big differences from each other. So for small continuity errors in a show or in this case the whole SBTB Franchise were seeing an alternate universe with a slight difference from the main one. While big errors are in drastically or somewhat drastically different universes. I'm not 100% educated on the topic of Alternate universes but from my knowledge this seems to be how it goes. Below I will say the universes we see that could explain inconsistencies in the franchise

The Main Universes:

Good Morning Ms Bliss Universe: A universe where Zack, Screech, Lisa and Mr. Belding all exist but live in Indiana and have friends like Mikey and Nikki as that universe's version of Slater and Jesse

Main SBTB Universe: The universe were accustomed to seeing with the six friends and their principal who live in Pacific Pallisades, go to Bayside and get into wild hijinks consistently including going to Malibu Sands and Palm Springs .

Toriverse: A universe very similar to the main one, however Kelly and Jesse do not exist (or at the very least left Bayside for unknown circumstances) and Zack, Lisa, Screech and Slater have been friends throughout all of High school and still got into wacky situations. In Season 4 it seems we switch back and forth from the main (or a universe resembles the main universe) universe to the Tori Universe. It also seems Season 1 of Saved by the Bell: The New Class takes place in this universe as Little Zack exists in that show.

Hawaiian Style Universe: This universe is actually the same as the main one but the only difference is instead of going to Malibu Sands before Senior Year they went to Hawaii in this universe (it takes place before their senior year as Zack is 18 and Mr. Belding says he'll see them next September meaning they still go to Bayside). This event can't fit in the main universe as Zack never mentions this event in "Best Summer of My Life" and as I mentioned before Mr. Belding tells them he’ll see them in September, which means it can’t take place in between season four and The College Years. But Slater and Jessie weren’t dating the summer after their junior year so it must be an alternate universe.

New Class Universes (that probably no one cares for but I want to explain) :

SBTB New Class Season 2 Universe: This season could ve been in the main universe but with references to both Main Universe and Toriverse as well as Bayside renovation that causes inconsistencies. In addition to that three characters from Season 1 vanish with no explanation (Scott, Vicki and Weasel). This season is in it's own universe. To add on College Years probably takes place in this universe as it makes no sense that Zack, Kelly, Slater and Screech go to the Same university when they all got accepted and were planning on going to different schools like Yale for Zack, Iowa for Slater and a local community college for Kelly. So this must also be universe where the guys applied to CalU all instead and Kelly transferred there rather than going to other schools like the original show implies. Lastly Zack, Slater and Lisa appear in this season with Screech and indirectly reference the marriage in Wedding in Las Vegas.

SBTB New Class Season 3 Universe: Three characters from Season 2 disappear with no explanation at all (Meghan, Bobby and Brian) meaning this is a whole new universe where those characters don't exist

SBTB New Clas Season 4-7 Universe: Three Characters from Season 3 left the show (Tommy D, Rachel and RJ) and while two got explanations as to where they went, one of them was just forgotten about (RJ). So this can't be connected to Season 3. The characters who leave after Season 4 get legitament reasons as to why the left, connecting the this universe but this timeline doesn't seem to follow the Main Universe or Toriverse so it must be in it's own universe as the Bayside High Setting has been changed but yet they continue to act it's always looked like that.

Overall this is my breakdown on why Saved by the Bell (or any show) can be inconsistent without any reason, as we maybe seeing an alternate universe where it can range from little diffeneces to humongous differences.