I once watched the extended cut in a cinema, all in one sitting. If I remember correctly, we started at 9 in the morning and went home after 10 in the evening. It was really cool. There weren't many people attending. We got Chinese takeout in between and ate it during the second one, the cinema didn't care about people bringing in food. Some people a few rows away looked at us annoyed. Might've been the smell, but I think they were just jealous that we had real food.