Graduation - S5-E24
Factual error: In the episode Class Pre-Union, they were the class of 2000. In the episode Graduation, they were the class of 1998.
Continuity mistake: If you look in most of the scenes, especially the one where she is throwing the stuff out the window, you can see a wall out of the window, but in the scene where Cory comes back from seeing the lady you can see a dresser out the window.
The Witches of Pennbrook - S5-E5
Plot hole: In this episode Cory takes Topanga on her "first airplane ride". But in season three (episode 66), Topanga had to go Disney World and she obviously took a plane.
Continuity mistake: In this episode Eric said he was 8 months older than Jack, but in '5-17 And Then There Was Shawn', Jack said that he was older.
Factual error: When Shawn has first infiltrated the college philosophy class, the professor begins to resume the class' previous lesson on what he calls "Buridan's paradox," relating a dog caught equidistant between two bowls of food. This paradox in real life is known as "Buridan's ass," and as the name would suggest, concerns a donkey. While the name was probably changed to sound more family friendly, a college philosophy professor would certainly know the proper name and details of said paradox.
A Very Topanga Christmas - S5-E11
Continuity mistake: When Topanga tries the egg nog, you can tell that there is nothing in the paper cup.
Graduation - S5-E24
Audio problem: When Mr. Feeny is reading off the names of all the graduates, you can hear reverb in his voice to indicate that he is speaking into a microphone. The problem is there is no microphone in front of him. You can see Eric holding the microphone next to him and singing into it, with no audio. If that microphone is turned off, then Feeny's voice should not be amplified. If the microphone is on, then we should also hear Eric as he is singing. (00:19:38 - 00:20:56)
Graduation - S5-E24
Continuity mistake: When Jack is showing Shawn the framed caricature drawing, both his hands are holding the frame around the middle of each vertical side. When the shot changes, his left hand is suddenly holding the frame by the bottom corner. (00:06:10)
Continuity mistake: After Topanga angrily walks out of Cory's house, he gets out of his chair and says "She really left," with his arms and fingers outstretched. When the shot changes, his fingers on both hands are curled into loose fists. (00:12:40)
Factual error: When Topanga and Ricky are looking at the Starry Night painting, Topanga reads from her pamphlet and says it mentions Vincent Van Gogh became religious around the time he painted it. Van Gogh grew up in a religious household, with his father being a minister of the Dutch Reformed Church, and Vincent himself actually had a desire to become a pastor. On the contrary, however, when he painted Starry Night, although he still believed in an afterlife, he was actually disillusioned with religion.
If You Can't Be With the One You Love... - S5-E18
Continuity mistake: When Shawn is cracking open his beer, he grips the top of the paper bag between his forearm and upper arm, with the top of the bag level with his shoulder. When the shot changes, the bag is suddenly lower. (00:09:15)
If You Can't Be With the One You Love... - S5-E18
Continuity mistake: When the transient is asking Cory if he's a cop, he points his right-hand index finger at him. When the shot changes, his index finger is curled onto his thumb. (00:08:20)
And Then There Was Shawn - S5-E17
Revealing mistake: When Shawn unmasks the killer and it is revealed to be himself, you can see that the body double that does the unmasking has sideburns and extra scruff on the back of his neck, making him noticeably distinct from Shawn. (00:18:17)
And Then There Was Shawn - S5-E17
Continuity mistake: After Eric rips the receiver and cable off the pay phone, at first he is holding the receiver in his right hand and the cable in the left. A couple of shots later, the receiver and cable have swapped hands. (00:15:15)
And Then There Was Shawn - S5-E17
Continuity mistake: When Shawn is grilling Kenny about asking to borrow Topanga's pencil, sometimes there is a female student sitting directly behind Angela with an open book on her desk, and other times the desk is unoccupied altogether. (00:00:21 - 00:02:40)
Torn Between Two Lovers (Feeling Like a Fool) - S5-E16
Continuity mistake: When Eric is saying "You think I should be a teacher," Mr. Feeny has his hands on his hips. When the shot changes, his arms are down by his sides. (00:15:42)
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)
The Eskimo - S5-E13
Factual error: When Shawn and all the other contestants - as well as the radio DJs and onlookers - are standing out in the cold for a chance to win Super Bowl tickets, no-one's breath is visible, nor are any parts of their faces red.
The Eskimo - S5-E13
Other mistake: When Shawn is saying "Thanks a lot Topanga" after she falls to the floor, he is looking down directly in front of him, but she is to his left.
The Eskimo - S5-E13
Continuity mistake: When Jack is asking Eric about his date the previous night, Eric puts down the book he was reading with the spine facing towards Jack. When the shot changes, the book has now rotated almost 90° counter-clockwise. (00:03:56)
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.