no its not a dream! its what happend before the accedint as shown in nfs u2 then in nfs u2 when you recovered your friend couldnt help you anymore so you have to go to bayview to let reachel help you out to keep on racing!
The odd thing about the beginning cutscene of NFSU2 is that the city where it takes place is actually Bayview if you look closely. If you think I'm talking bullshit, see for yourself
See? Bayview, not Olympic City.
That's probably because Olympic City isn't in NFSU2's code, so they lacked roads from OC to put the flashback on.