Factual error: In this episode, Eric and Cory stop in Pottstown, Pennsylvania on their way back to Philadelphia. Cory protests, reasoning that stopping there is pointless because they are only three hours from home. Pottstown is roughly 40 miles from Philadelphia. It certainly wouldn't take three hours to get to one location from the other under normal driving conditions.
Continuity mistake: At the end of the episode, when Cory and Topanga are kissing, Shawn says "Hey, I'm talking to you", hits Topanga on the arm and her hair gets messed up. When the shot changes to a wider view, her hair is not messed up. The position of Topanga's arms wrapped around Cory also changes.
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.