Other mistake: At the beginning of the episode, Eric talks about how Alan's Navy background will cause him to use any means necessary including torture to find out about his birthday party. Cory chimes in and states that Alan was a cook in the Coast Guard. The plot of the Season 1 episode Kid Gloves concerned a necklace Alan gave Cory for his birthday, which Alan himself earned for placing second in his weight class for boxing in the entire Navy. So either Cory doesn't correctly remember his own father's military background, or the show needlessly retconned it. (00:00:43)
Continuity mistake: This episode is during Christmas time and it's Alan's birthday, but it was mentioned in "Honesty Night" that Alan's birthday is June 14th.
Character mistake: After Cory and Topanga have their argument in front of everyone, Cory remarks to Shawn that it's their first fight ever. Cory and Topanga had several fights in the show prior to this. (00:12:50)
Continuity mistake: When Cory is lying on the couch during his argument with Topanga, the pink pillow is under his right shoulder. A few shots later, it is suddenly under his neck. (00:17:00)
I'm Gonna Be Like You, Dad - S7-E14
Continuity mistake: When Topanga, Shawn and Angela are hanging out in Cory and Topanga's dorm anticipating Cory's return from the doctor, the slice of pizza that Angela is eating goes from having a small bite taken out of it, to being halfway gone, and back to having one bite taken out of it. (00:12:07 - 00:14:02)
The War (1) - S7-E15
Continuity mistake: After Rachel sprays water all over Cory, the amount of wetness on his shirt varies throughout the scene. (00:05:53 - 00:09:05)
The War (1) - S7-E15
Continuity mistake: When the show starts, Angela and Shawn are kissing. The shot changes to Topanga and Cory, who has popcorn on his shirt. The shot goes back to Shawn and Angela, when Cory is shown again, the popcorn is gone. Again the shot changes to Shawn and Angela, then back to Cory and the popcorn reappears.
Seven the Hard Way (2) - S7-E16
Continuity mistake: When Topanga joins the group hug, the piece of paper that Eric wrote on is underneath her. When Cory joins in, the paper has disappeared. It then reappears when Mr. Feeny dismisses everyone. (00:20:10 - 00:20:45)
She's Having My Baby Back Ribs - S7-E17
Continuity mistake: When Jack, Rachel and Angela start heading to their class, a shot of Topanga shows her holding a slice of pizza slightly raised from her plate. When the shot changes, she is suddenly holding the pizza several inches above the plate. (00:01:04)
She's Having My Baby Back Ribs - S7-E17
Continuity mistake: At the start, in Cory and Topanga's dorm room, Topanga asks if Cory thinks she is attractive. He says "Of course I do. Come here, I'll prove it" and leans on his side and tilted back. When the shot changes after Topanga starts walking towards the closet, he is suddenly sitting upright. (00:03:29)
She's Having My Baby Back Ribs - S7-E17
Continuity mistake: When Cory gets off the bed he leans against the dresser and his hands are behind him. When Topanga walks in the room, his hands are by his sides. (00:03:50)
She's Having My Baby Back Ribs - S7-E17
Continuity mistake: After Cory says "You don't have to tell me that" after Shawn compliments his waffles, Shawn is shown holding the fork pointed down towards the waffles. When the shot changes, he is suddenly holding holding the fork perpendicular to his body. (00:04:35)
She's Having My Baby Back Ribs - S7-E17
Continuity mistake: When Alan remarks that Amy never got her figure back after she gave birth to Eric, her arms are folded. When the shot changes, her arms are down at her sides. (00:10:10)
How Cory and Topanga Got Their Groove Back - S7-E18
Continuity mistake: When Eric sneezes on Jack's cereal, Jack is holding the carton of milk level with his abdomen. When the shot changes, he has already set the carton down on the counter. (00:04:30)
How Cory and Topanga Got Their Groove Back - S7-E18
Continuity mistake: Cory is walking around taking back flyers he'd earlier passed out. In one shot he grabs a flyer out of a young man's hand but in the very next shot, the young man is still holding the flyer. (00:08:57)
How Cory and Topanga Got Their Groove Back - S7-E18
Continuity mistake: When Eric is saying to Jack "It was you all along," he points his left-hand index finger at Jack, who is shown writing down the lottery numbers Eric provided him. When the shot changes, Eric is now pointing with his right hand, and Jack's hands are suddenly on his hips. (00:16:40)
Continuity mistake: When Topanga puts the bucket in the garbage bag, she is holding the bag with her left arm and has her right arm in it. In the next shot, she is holding the bag with her right arm. (00:00:36)
Continuity mistake: When Eric purchases Rachel's tank top, the placement of his right hand while holding it changes when he says "I'm a collector." (00:10:43)
Continuity mistake: When Cory is telling Topanga that he wants to be sure Wile E. Coyote will be all right, you can see a single piece of popcorn on the right side of the microwave stand in the background. When the camera switches back to Cory after Topanga assures him he's always all right, the piece of popcorn is now gone. The amount of popcorn on Cory's shirt also decreases in both aforementioned shots. (00:02:15)
Continuity mistake: When Topanga gets sucked into the time continuum vortex, you can see a teddy bear between the skis and a pair of shoes. When the shot changes to Cory, you can see the skis and the pair of shoes, but the teddy bear is now missing. (00:04:03 - 00:04:33)
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.