Hi,
Here is the official help from Schema.org : https://developers.google.com/structured-data/critic-reviews
I’m far from a programmer (I’m more a business analyst/demand manager), but if you’re using a specific variable for the name, IMDB adress of the movie, producer/actor, it should easy to call these informations on a specific script for the snippet. If you download the required informations for the snippet, I think this is enought for the beginning of a good snippet ??
If you want some help or tests, I’m here !