*SPOILERS*
There were a LOT of things in TP that we saw in trailers and didn't get with the finished package.
There was no level with ghosts of soldiers if I recall. I remember the trailer scrolled through a room of a level for a few seconds, and there were these spirits of dead soldiers everywhere (and I'm not talking about when you use your senses you can see people in the other realm kind of thing, I mean actual ghosts). Also, I remember a scene where Link is just standing there, then the Lens of Truth (assumed to be) kicked in, and there were ghost rats all over him. Of course, the rats were there in the final game, but the only way you could see them would be in wolf form.
It really upset me because at Hyrule Castle there is a part where you have to use your senses to see some spirits (whom you have never seen in the game prior) who point you in the right direction to go. It felt like an entire level was cut out from the game, but they for some reason left that part of the castle there unchanged (which had to do with the cut out level).
I remember bringing this exact subject up on another forum. I wonder if I could find it and bring some of what was said here...
For those of you who were wondering, I think that the spider in the trailer link was running away from was just Ghoma who they decided to make the Temple of Time boss, with different attacks of course.
There were a bunch of minor changes, like Midna's colour scheme, the Twilight realm changing from a grey tone to a sunset tone, small stuff like that.