For Love and Apartments - S7-E2
Character mistake: When Shawn is scolding Topanga for getting angry with Cory for travelling to Pittsburgh to try to get her parents back together, he mentions that he travelled a hundred miles to do so. Philadelphia is roughly 300 miles from Pittsburgh. Travelling only 100 miles westward from Philadelphia would barely get them past Hershey. (00:17:53)
Character mistake: At one point Cory is telling Shawn about how he can't protect Topanga and they've only been married for one week. But they spent their wedding night in jail, 12 days on their honeymoon and 1 night in their new apartment. So actually the couple have been married for 2 weeks.
Character mistake: After Cory and Topanga have their argument in front of everyone, Cory remarks to Shawn that it's their first fight ever. Cory and Topanga had several fights in the show prior to this. (00:12:50)
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.