When Tiffani-Amber and Elizabeth sign in to audition for the role of Kelly, the sign-in sheet shows Taylor Parker auditioning for the role of Jessie Spano. However, after Tiffani-Amber and Elizabeth audition, it's revealed there are only two female roles (Kelly and Lisa), and the producers wish to create a new role (Jessie) specifically for Elizabeth. Therefore the role of Jessie Spano couldn't have existed yet when the girls signed the sign-in sheet before the audition.
After the graduation scene, when Dustin does his "Time out!", all of the cast members are standing and talking to each other. After Dustin says "Time in!" the director comes and yells, "That is a wrap!" and everyone is suddenly seated neatly in chairs on the set. In the next shot of the stage, everyone's standing and mingling again.
After leaving Saved by the Bell (1989), Tiffani Thiessen and Elizabeth Berkley are depicted as returning to the series to film its final episode, Graduation (1992). In reality, the final broadcast episode was filmed before their departure.
Dustin Diamond says after Saved by the Bell: The College Years (1993) was canceled, he claims it was the last series of the franchise. But he didn't mention anything about Saved by the Bell: The New Class (1993) which is another incarnation that he and Dennis Haskins continued their roles as Screech and Mr. Belding for six more years.