Continuity mistake: When the gang watches an advanced copy of "The Wood", and Jade watches the fake phone call between Beck and Tori, the background and scene changes from Beck at School, in the day, to Tori at Home, at night (viewable through windows) This isn't noticed by Jade. (00:13:30)
Other mistake: In 1-7: 'Robarazzi', Robbie shows a video of Jade and Beck talking in a car. In the middle of the conversation, Jade states she had tuna fish for lunch, but in this episode, when Jade is listing things she hates, she lists "tuna fish".
Answer: Jade breaks up with Beck because he was hanging out with another girl, which she didn't like.
MattHellstrand