Continuity mistake: When Cory is saying to Lauren "Well, today I guess you're stuck with me," he slightly raises his left hand and then sets it back down on his left knee. When the shot changes, his left hand is suddenly resting on the couch cushion between his legs. (00:05:03)
Revealing mistake: When Topanga is picking up the letter off the ground, you can tell the snow isn't real because it doesn't behave like real snow and run together when she scrapes the letter against it. It looks more like shredded paper being swept aside. (00:20:38)
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.