While Tami and Eric are talking about Matt and Julie and the rally girl being pressured into a 3 way, it's mentioned that Julie's a sophomore, however, she's not a senior until the fourth season (fourth year of the show).
When the Taylors are in the kitchen preparing dinner together and Julie reveals that Matt Saracen asked her out on a date, a camera can be seen in the hallway on the right side of the screen.