No Such Thing as a Sure Thing - S7-E4
Revealing mistake: When the family is eating dinner, throughout the scene you can see Jack dabbing his fork into his mashed potatoes and raising the fork to his mouth with little to no potatoes on it in order to give the illusion that he is eating. (00:03:57 - 00:05:05)
No Such Thing as a Sure Thing - S7-E4
Revealing mistake: The pitchfork that the Amish girl throws at Eric at the end of the episode is obviously made of rubber, as it wobbles when he catches it.
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.