Continuity mistake: Trina throws Tori's laptop onto the couch next to them. About a minute later, Jade comes in to Tori and Trina's house, and sits on that couch, where the laptop originally was. The laptop is missing, and nobody could've moved it, because nobody was near the couch in between the two events.
Tori Fixes Beck and Jade - S4-E6
Audio problem: When Jade performs, you can tell she's lip syncing. (00:02:00)
Continuity mistake: Salt is visible on Jade's table before she gets the answer wrong and the salt pours on her from above.
Answer: The Director hated working with Melinda, but knew that her superstar popularity and status would get his movie a big buzz and higher ratings. And the movie was discontinued for a re-audition to fill-in Melinda's leading/major role.