actualy several of the keyblades we know that are in the video dont have keychains, they probably did without them because of simulation time of thousands of keyblades plus all the effects. i actualy do 3d cg and simulating one object is a hassle...it takes 3 seconds a frame...and thats one object, there was over a thousand in the video, imagine simulation time of that many key blades for a 5min film. also the 60 seconds a min and 30 frames per second(more or less)...(calculates) thats 9000 frames....(again) and that 450 mins(7.5 hours) for one key blade. now imagine the time for a thousand keyblades at the same time(probably some ware around 800hours depending(which would be 33.3 days or a month). maybe square enix didn't have the time....thats pretty sick time you know....those extra keyblades also add to render time which from the lighting, textures, material settings, GI(global illumination(jacks up time drasticly), ambient occlusion, particle effects, the aliasing passes....i'm thinking a minimum of 15 hours per frame....add those keychains could add an hours too it as well. but the thing is they use a render farm with set ups of allot of computers rendering frames. which would change that to something like 20 frames in 15 hours depending on how many computers are sett-up....
sorry...sometimes i get a head of my self when it comes to 3dart...i admire and look up to square enixs cutscenes greatly....