How could you get stuck? The speech before it leads up to the outcome pretty obviously.
I got stuck hard at..... SPOILERS
----- Guy at villa escaping in the helicopter. I shot it sooo many times, pieces were falling off, but he still flew away every time. Eventually I realized I had to RUN UP to the chopper and climb on, NOT SHOOT IT DOWN TO DISABLE IT. Made me chuckle.
Unofficial Underground Car Tuning/Street Racing Board http://boards.gamefaqs.com/gfaqs/gentopic.php?board=585168