There’s an effect in Shrek 2 that I don’t remember seeing elsewhere, though it doesn’t even need a completely animated universe: It switches scenes by keeping the lead character in close up, and simply fading one background out and another in at the same time. Not to be confused with the much more common “spin the camera around a couple while the backdrop changes”, which they polish off in the first five minutes.

There isn’t really anything else of merit in the film, apart from brute cleverness.