The Hole-in-the-Wall Gang - S4-E21
Other mistake: In the previous episode, when Jesse almost moved into Becky's apartment, Stephanie moved into Jesse's old room. Then it was decided that Jesse and Becky would turn the Tanner house attic into an apartment. However, Joey is now taking Jesse's old room, with no explanation. Stephanie has to share a room with DJ again. This does not make sense because, with Jesse living in the attic, his room would still be available for Stephanie.
The Hole-in-the-Wall Gang - S4-E21
Plot hole: When Stephanie and DJ start singing that dad song in their room, Michelle come in and starts singing. After she goes, DJ and Stephanie have a talk. After two minutes, Michelle comes in, dressed like they are. How could a 4-year-old girl change to teenage clothes and fix her hair in two minutes? Danny was in his room (because he found the baking soda), and Jesse and Joey were too busy with Jesse and Becky's room to help her change.
Suggested correction: However it could have been Kimmy as she was seen in the tanner house hold not that earlier in that episode and may have never left.