A Very Topanga Christmas - S5-E11
Factual error: This episode takes place near and on Christmas, but an establishing shot of the Matthews' house early in the episode shows the trees to still have very green leaves, and outdoor plants and the front lawn are still alive and healthy looking. None of this is possible in winter in Philadelphia.
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.