When you search for a movie, there are small icons to indicate if it has already been added to your Watchlist, Collection, etc. However, when you're browsing one of these lists, there are no icons to quickly show you quick movies are also on another list.
For example, when browsing my Watchlist, it'd be very useful to quickly see which ones are also in my Collection.
Although seeing Collection icon when browsing Watchlist, and vice versa, would be very very useful, I realize this would clutter the beautiful streamlined view of movie posters. But we should at least see this info on the main details page for a movie, without having to click on the little arrow to pull up the separate window, as currently implemented.