Visible crew/equipment: After Mr. Feeny says "You are the graduating class of the year 2000," he turns around in front of the back wall. As he turns around, there is a shadow of possibly a boom mic on the back wall which moves as Mr. Feeny moves. (00:04:15)
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)
The Pink Flamingo Kid - S3-E17
Visible crew/equipment: After Amy says to Eric, "Whatever makes you and Kyle happy", the shot changes and a boom mic can be seen being pulled out of view on the left side of the screen.
Visible crew/equipment: When Eric jumps out of his chair and exclaims "No" during his college acceptance interview, a boom mic can be seen being pulled out of view. (00:19:00)
Visible crew/equipment: After Amy's C-section Alan walks into the waiting area, and just as his kids gather around him in the wide shot the boom mic dips into view at the top, center of the screen between Alan and the plant (viewed on iPad screen). (00:20:10)
Visible crew/equipment: When Topanga carries Cory into the room you can see a crew member's hand triggering the doors to open.
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.