At this site people report mistakes they saw in movies. The owner of the site doesn't contribute much mistakes himself. So this site is based on participation.
Also if a mistake you send to the site isn't really in the movie, other participants report this. So this site is correcting itself.
A while after this site became populair, the owner gave users the availability to see the mistakes for themselves. iMMAGES AND BOVIES ARE PROVIDED. But you have to be a member.
There's a forum aswell, so check it out!