Reflective sentences don't simply describe a movie, a book, a world event, etc. They tell the reader:
What you think Example: The movie really helped me understand what it's like to be a doctor.
How you felt Example 1: My heart was pounding in fear when I read the scene with the electroshock therapy. It was awful that they did that to people.
Example 2: I was shocked to learn that Mr. Singer was blind, too. How could he have fooled people for so long. That totally surprised me.
What you'd do if you were there Example: If I were the judge, I would have sent Barnard to prison for 20 years, not let him off with a warning.
What you think will happen Example: This relationship between Anna and Mike can't last. Susan is bound to find out about it and then, watch out!
How the movie/book/story/event relates to your life Example: The scene with the cat and the mouse grabbed my attention, because I lost a cat, too, and my cat loved to chase mice just like the cat in the story.
Anything else that comes into your mind Example: This chapter reminded me of the scene in A Raisin in the Sun, when the mother finally receives the $10,000 check in the mail.