I saw it.
Brian gets hit with his own car.
There's some temporal shenanigans going on.
I'm not even kidding: I haven't seen an episode where Brian drives his Prius (or whatever it is) in a while, but the moment I saw the car that was going to hit him, the first thing that popped into my head was "that's Brian's car." So, regardless of Stewie destroying his time machine, I'm of the mind that there's still time-travelling going on somehow.
We'll have to wait and see, though. I haven't seen anyone else mention it, so I'm likely wrong. I just thought it was odd that a.)they looked really similar, and b.)nowhere in the episode did anyone ever express any interest in trying to find the car that hit him, like they didn't want to draw attention to the fact that you don't know who the drive is ('cause it's Brian).