Kids are always curious about movies and sometimes you run a movie on TV that you remember to be fully innocent only to find it has a scene that you’d forgotten about that is really not appropriate. There are some great websites to help you figure out what is going on in the movies BEFORE you play them.
Common Sense Media is one place to research. Another is Parent Previews. And yet another is Clear Play that has a DVD player that you can buy which will bypass and bleep out all objectionable words and scenes.
Okay, now, as a parent (or a babysitter, or an aunt or uncle), you are protected!