Top 250 list

I am currently on a mission to watch every movie on the top 250 list. I noticed however that the movie Pather Panchali fell out of the list despite it's rating being 8,2 with a lot more than 25k votes (it has 39k). Why is this movie not featured in the list above movies with a 8,1 rating?

Also if you could clearify why the movie 12th Fail (top rated movie #58) with a rating of 9.0 is not higher on the list and above movies with a 8.4 rating? 
I know you may not disclose exactly how your rating system functions, but I hope you are able to clear up my confusion. My guess is it has something to do with amount of votes and maybe what users have voted.