In "A Little Romance" D.J. says she has a purple belt in karate. But a couple episodes later, she says she is just about to get a green belt. Purple belts are supposed to come after the green belts in karate.
When Jesse and Becky kiss in the kitchen, her arms hang at her sides. When they stop to look at Michelle, her hand slides off his shoulder like it's been there the whole time.
When D.J. kicks Steph out and she is sleeping on the floor in Michelle's room. Nick comes in to check on Michelle, Steph is asleep. When Nick leaves the room, Michelle goes to throw a pillow at Steph, Steph's eyes are open, then right before the pillow hits her she closes them.
When the girls' grandpa, Nick, goes to check on Michelle, he walks into her room and closes the door. Then when he leaves a few minutes later, the door is open again.