The Birds and the Frozen Bees - S7-E23
Continuity mistake: Roseanne and Darlene are sitting on the sofa discussing Darlene getting back together with David. The cuff on the sleeve of Darlene's sweater is partially turned down, and in the next shot it's neatly turned up.
Chosen answer: Rachel attended college, but in one of the Thanksgiving flashback episodes she mentions that her major was psychology but there was no parking around the psychology building, so she switched majors. She never says what her new major was.