Visible crew/equipment: In the scene where Zack talks to Jessie about switching desks to be next to Kelly, you can see the top of the set for quite a few seconds including lighting, scaffolding and tops of the adjoining rooms. (00:06:15)
Continuity mistake: In the scene where Max has Zack bring Kelly a Coke, you can see the glass only has one straw in it. You can verify that it's simply not two straws stuck together when he lays it on Kelly's table. As he lays it down, the straw swoops around the outer perimeter of the glass and it can be verified that it's only one straw. However, when Kelly decides to take a drink of it there are now two straws in the glass.
Plot hole: Zack was told by Slater that Kelly was excused from going to detention by Belding because Belding found out she saved Screech's life... Yet only 3 students knew about the fake "choking" stunt - Zack and Screech did this stunt to get Kelly into detention (so they wouldn't have said anything), and Kelly unlikely would say anything as generally students will say anything to get excused and usually are ignored by the teacher or principal who use authority to make the student's detention stand. So who else could have told Belding?
Answer: The show that took place in Indiana that you are referring to was titled "Good Morning Miss Bliss." This show only lasted one season. The kids on the show, however, were popular so they decided to create a spin-off titled "Saved By the Bell," that aired on Saturday Mornings. I'm sure they changed the location because they thought the California setting would make the show more fun and watchable for pre-teens and teens.
ACertainShadeofGreen