Revealing mistake: While the girl who just broke up with her boyfriend is on the phone with the ex, she is throwing his stuff out the window. As she throws the last couple of CDs out the window, you can see the backdrop of the beach sway a little bit.
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)
Revealing mistake: You can tell the ocean visible from the dorm room window is just a backdrop, as there are no waves approaching the shoreline.
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.