If the man does not respond to your plea to move his car forward so you can see if your car is damaged, try restating your request.
If he then addresses you in Spanish, try using simpler English words.
If you can't figure out what he wants to do regarding the accident, suggest that you call the police to report the accident.
Watch the reaction you get when you mention "police".
Honestly, it didn't occur to me that attempting to report an accident could be taken as a threat; I certainly didn't mean it that way. It was only after I saw the panic on the man's face that it hit me what might be going on (other than fear of post-accident car insurance rates).
Since he wouldn't move forward, I backed up my car (don't know why I didn't do that in the first place...I think it's because there were pedestrians nearby behind me) and determined there was no obvious damage and we should depart the scene and not worry about reporting it. He looked at me pleadingly and made me promise not to call the police. I promised, but on the surface, it was kind of a funny idea; even if I was the kind of person who wanted to help deport possibly illegal immigrants, what good would calling the cops after the fact do? I hardly think a vague description of a Hispanic man in a white truck would send in the Border patrol.
Anyway, I am fine, the car is fine, and hopefully the man in the white truck will pay better attention to his rearview mirror next time he reverses.