What are some things I can do with my friend to get her mind off of a car accident?

Why not go for a walk and let her talk about it? She is going to have to work through it until she can let go of whatever is holding her to that scene. As you realize, it's not really possible to do anything to make her not think about it, but something physical would probably give her at least minutes of respite from it - if she can enjoy herself at all right now. You don't say how long ago this happened, but if it's within the past week - she is still traumatized by it and just needs time and some support/understanding from her friends and family.

Ask her what she would like to do and what does she think might help her the most right now. If you both like to bowl or skate or exercise, or some other physical activity, I would encourage you to include that as it gives her body a way to release some of the emotions she is carrying.

You're a good friend for asking this question and realizing that watching a movie is probably not going to work. But she may also say "I don't know, whatever you want to do" in which case, you might ask if she WANTS to talk about it. If she says no and you still think a movie won't do it, go play somewhere - or go have coffee or an ice cream or somewhere that is neutral territory. Unless she says she just needs to sit with you and be safe. And perhaps that really is all she needs. Just to be where she is safe and not judged or badgered about it.

One thing you can do for her is to bring calm and peace into yourself so you can offer her your presence without adding to her stress.

Good luck!