That was one of my guesses. I just didn't remember it from the first movie. I was hoping it was teasing that there'd be a part 3. Kinda like the garfield 3 movie, which I'm pretty sure wasn't real. Maybe just wishful thinking and seeing patterns where none exist.
Think its when they find the hummer loaded with guns that you see him painting a big 3 on it, or it was on the side of the suburban the girls stole from them but it's there.