Continuity mistake: When Shawn is saying to Cory "No pudding, no 'Woo-hooing'," Cory is holding a cup of pudding with his arms raised to around his chest area. When the shot changes, his arms are suddenly down at his sides. (00:01:17)
And in Case I Don't See Ya - S6-E10
Continuity mistake: When Cory, Shawn and Feeny are at the table, Feeny's glass is almost half full. Cory later fills it up, but in the next shot the glass is half full again. In a later shot it's full and then it's somewhere in between half full and filled up.
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.