I was rewatching this the other day, and I really got the impression that this felt much more like a PG-13 movie than an R rated movie. Yes, there was violence, but it didn't feel over the top or more than what could be handled in a PG-13 movie. I don't know if anybody else agrees, I just thought it was kind of odd, seeing as how even if they did get an R rating to begin with, they could probably have appealed it to get the rating lowered.
It was probably rated R because of different things other then it being 'scary' or 'violent'. Like the mental illness with the dad, and I'm not sure since I haven't seen it in awhile but if they said the F-word more then once that may be another reason why, and just for the fact that a child who is surrounded by all the violent natures of the father could probably be another reason. I am not all that sure, but that could be why it earned an R rather than a PG-13. But, honestly, when I first watched it I thought it was PG-13.
Man-Curiousity killed the cat
Officer-That still doesn't explain why you killed that boys cat.
Film ratings are not always due to violence and language. The film had a psychological plot so I'm not sure that younger children would have fully understood that Emily's dad was "Charlie". And there was some violence, the mother commits suicide (even though you don't see it you see blood in the bath), the cat that Emily had is killed and I guess the shooting of David at the end counts as violence too.
No guy is worth your tears, and the one who is won't make you cry