You know, she actually was mentioned in the film. At the party where Scott first talks to Ramona. He's talking to Julie.
I don't remember Scott's lines exactly, so I'm just... approximating what he says.
Julie: "Everyone knows you're a ladykiller wannabe jerky jerk."
Scott: "That is so not true!"
Julie: "That time with Lisa?"
Scott: "That was nothing."
Julie: "That time with Hollie?"
Scott: "Nothing happened."
Julie: "That time with Kim?"
Scott: "Oh, come on, Kim? We're totally cool now."
[Scott turns and Kim is glaring at him from across the room.]
(Again, I don't remember Scott's lines exactly, so please don't ridicule me about that.)
It's a quick line, so not many have caught it... but wait, how does Julie know Lisa? Lisa was the girl that Scott met on the first day of high school after getting into a fight. They soon formed a band with Kim at roughly the same time Scott and Kim began dating. Then Scott moved to Toronto (where he met Julie, Envy, Stephen Stills, Young Neil, etc.) and Kim followed a couple years later. They went through college and the stuff with Envy and Scott happened; Stephen Stills and Julie began their long on-and-off relationship, etc.; and then they get out of college, Sex Bob-Omb is formed somewhere in that time frame, and then it picks up on present events. Julie doesn't meet Lisa until Lisa is visiting Toronto in volume 4.
But, obviously, the movie is way different than the comics. I think I'm going to go make a thread about that, actually. xD