Continuity mistake: When Cory is getting food for Shawn, he's piling meat loaf onto his plate. There are three pieces, one on top of the other two, then they cut to a wide shot and back to a close up of Cory, and it's just one larger piece.
Revealing mistake: When Cory writes "Hey Dude" on the chalkboard, you can see how it had been written and erased several times, indicating previous takes.
Santa's Little Helper - S1-E10
Visible crew/equipment: After the bell rings and Mr Feeny says "Have a wonderful vacation," a boom mic can be seen dropping from the top left of the screen as the students are rushing out of the classroom. (00:17:20)
Continuity mistake: When Mr. Feeny says "As if you are returning for your 20th high school reunion", there is a red crown on Mr. Feeny's desk with Minkus sitting on a chair at the end. After the camera cuts to a close up of Minkus saying 'More like a pre-union", there is a cut to Mr Feeny who turns to him. Minkus is all of a sudden holding the crown on his lap, then he is seen putting the crown back onto the desk. (00:04:00)
Continuity mistake: When Alan is talking to Cory in his room, telling him that he can always come home, he is pointing his finger at him. He has his right arm rested on his legs and is pointing with the left arm. Just before the shot changes to face Cory, Alan stops pointing. In the next shot, facing Cory, Alan has his left arm resting, and is pointing with his right arm.
Answer: Topanga's middle name is never specified. Considering her sister's name is Nebula Stop-the-war Lawrence, Topanga's is probably something equally unusual.