Continuity mistake: After Topanga draws a lipstick heart around her face and Shawn says "Use a mirror, babe," a closeup is shown of Topanga smiling at Shawn and you can see Cory has lipstick on his forehead before Topanga has drawn it on him. (00:20:30)
Visible crew/equipment: After Amy's C-section Alan walks into the waiting area, and just as his kids gather around him in the wide shot the boom mic dips into view at the top, center of the screen between Alan and the plant (viewed on iPad screen). (00:20:10)
Continuity mistake: After Eric smears his hands all over Topanga's face, the amount of skin cream on her right cheek drastically decreases when she is telling Cory she's going to go wash her face. (00:14:35 - 00:15:00)
Can I Help to Cheer You? - S6-E18
Continuity mistake: When Tommy is saying to Eric "We've been hanging out with each other for a long time now," Eric's coffee mug is mere inches from his face. When the shot changes, the mug is almost set down on the table. (00:00:58)
And in Case I Don't See Ya - S6-E10
Continuity mistake: When Mr. Feeny is looking over Cory and Shawn's papers, he rests Shawn's paper on the plate with his omelet. When the shot changes, he is holding the paper in his left hand and it is raised away from the plate. (00:18:35)
We'll Have A Good Time Then - S6-E13
Continuity mistake: The picture Rachel takes of Shawn, Jack and Chet is not consistent with the framed picture Jack receives. When Rachel takes the picture, Shawn's necklace is sticking out of his shirt collar slightly and positioned to the right and he has a lock of hair draped over his forehead on the left side of his face. In the framed picture, his necklace is protruding from his collar more prominently and positioned to the left, he has no lock of hair over his forehead, and his left hand can suddenly be seen on Chet's left shoulder. Additionally, the framed picture shows Chet with his head slightly tilted back and showing his teeth as he smiles, but when the picture was taken, his head was level and he only had a slight grin with no teeth showing. (00:04:49 - 00:21:10)
Santa's Little Helpers - S6-E11
Continuity mistake: When Shawn and Angela are talking in the student union building, Shawn's scarf is draped around his neck in an asymmetrical fashion, with the left side shorter than the right. When they sit down on the couch, he pulls the two sides to a symmetrical length. Throughout the rest of the time Shawn remains seated on the couch, the two sides alternate between being symmetrical and asymmetrical. (00:15:20 - 00:16:47)
Better than Average Cory - S6-E5
Continuity mistake: When Rachel starts writing down that she is choking, she knocks a cup of water off the counter. After she spits out the hot dog she was choking on, the cup has reappeared on the counter. (00:06:38 - 00:07:00)
Continuity mistake: When Eric and Jack place the red tablecloth on their counter, it barely drapes over the end of the counter that is facing the camera and completely covers the side that is on the viewer's left. A couple of shots later, the tablecloth is draped over the same end of the counter down to the floor, and the left side is now exposed. (00:05:06)
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)
Continuity mistake: When Rachel tackles Jack onto the couch and is straddling him, Jack's head ends up resting on the green and yellow pillow on the cushion closest to the door. After Jack says "She's sittin' on me, man," the shot changes and his head is now on the middle cushion. (00:16:06)
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.