Change criteria for a 'rare' movie
The criteria for a rare film on Movielens have some very weird results sometimes. For example, my list for the rarest movies I have rated lists films like 'Drinking Buddies' or 'Romantics Anonymous' alongside 'Now You See Me' or 'Snow White and the Huntsman'.
Now, I doubt that anyone would consider movies that make more than 300 Mio. as rare. I assume this is due to a certain selection bias, because movielens users are naturally more interested in rare movies than the general population.
I think this problem could be fixed very easily if you use the number of imdb ratings instead.