A Long Walk To Pittsburgh (2) - S4-E17
Character mistake: In this episode Cory says that Topanga gave him his first kiss at age 13, but their first kiss actually happened when they were 11, in the 6th grade. (Season 1 - Episode 7 Cory's Alternative Friends).
A Long Walk To Pittsburgh (2) - S4-E17
Continuity mistake: When Topanga comes back to see Cory, for the whole period of time that she is there, sometimes her hair is dry and straight, and others it's wet and wavy. (00:07:12 - 00:21:16)
A Long Walk To Pittsburgh (2) - S4-E17
Continuity mistake: After Cory finishes explaining to Amy why he loves Topanga, he sits down next to her and begins placing his arm around her. When the shot changes, his hand is instantly resting on her shoulder.
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.